Documents

Low Voltage Models Added to ZWS300BAF Series

Nortski — Fri, 08 Oct 2021 07:52:49 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 7:52:49 AM

TDK Corporation introduces the addition of 12V and 15V models to its TDK-Lambda ZWS300BAF series of high reliability power supplies. Operating from a universal input of 85 to 265Vac, the ZWS300BAF features a 10-year electrolytic capacitor lifetime demanded by manufacturers of industrial, test & measurement, broadcast and communications equipment.

The ZWS300BAF series now comprises of 12V, 15V, 24V, 36V and 48V models, each adjustable by up to +/-10% to accommodate non-standard system voltages. Standard features include over current and over voltage protection and an optional remote on/off or cover is also available. Achieving up to 89% efficiency for the 12V and 15V models, the ZWS300BAF has an operating temperature range of -10 to +70^oC, allowing 100% load operation in a 40^oC convection cooled environment and 60% load at 70^oC with 1.4m/s airflow.

With active Power Factor Correction that meets IEC61000-3-2, the ZWS300BAF has a 3kVac input to output isolation and meets conducted and radiated EMC conforming to EN55011/EN55022B and FCC-B. Delivered with TDK-Lambda’s 5 year warranty, the ZWS300BAF is safety certified to UL/CSA/EN60950-1, EN50178 and carries the CE mark to the LV and RoHS Directives.

More information can be obtained at the following TDK-Lambda Americas website, http://www.us.tdk-lambda.com/lp/products/zws-series.htm, or by calling 800-LAMBDA-4. Product availability for the ZWS300BAF series can be found via the link to TDK-Lambda’s distributor network (see “Check Distributor Stock to Buy”) athttp://www.us.tdk-lambda.com/lp/.

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Major applications

Industrial, COTS (Commercial Off The Shelf), test and measurement, broadcast and communications equipment.

Main features and benefits

Up to 91% efficient (24V output)
10-year electrolytic capacitor life
Five Year Warranty
Convection and forced air ratings

Major specifications

Model		ZWS300BAF-12	ZWS300BAF-15
Input voltage range	Vac	85 to 265
Nominal output voltage	Vdc	12	15
Nominal output current	A	25	20 (22 with forced air)
Output power	W	300	300 - 330
Efficiency (200Vac Input)	%	89
Operating ambient temperature	°C	Convection: -10°C to +70°C derating linearly to 40% load from 40°C to 70° 1.4m/s Airflow: -10°C to +70°C, derating linearly to 60% load from 50°C to 70°C
Safety	-	UL/CSA/EN 60950-1, CE Mark (LV & RoHS Directives)
Size (W x H x D)	mm	84 x 42 x 180
Warranty	Years	Five

Tags: 12v, zws300baf, 15v, power_supply, zws

The advantages of using a power supply incorporating digital control to power non-linear loads

Nortski — Fri, 08 Oct 2021 07:52:26 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 7:52:26 AM

I was recently tasked with doing a presentation on the advantages of power supplies incorporating Digital Control to power non-linear loads, so I thought I would share the content with you.

A non-linear load is one that does not behave like an ideal resistor, in that the current drawn from the power supply is not proportional to voltage and/or the initial currents are often much higher than the rating of the power supply.

These loads can cause problems for power supplies, but are actually present in many applications:

Large switched capacitor banks

Point of Load DC-DC converters

Thermal printers

DC motors

The main issue from a power supply’s point of view is that the load can activate the internal over-current protection. Over-current protection (OCP) is an essential feature for a power supply, but the power supply is usually expected to recover automatically with no manual intervention.

So to start with, let’s look at the types of OCP. There are several basic methods used:

Constant Current

Fold Back

Fold Forward

Hiccup

Constant Current

When an overload condition occurs, the output voltage falls but the output current remains at a fixed level. This type of protection is not well suited for delivering peak loads as it can lead to the power supply latching.

Fold back

When the current drawn reaches the OCP limit, the voltage falls, but this time the current decreases as the overload gets heavier. Again this type of protection is not well suited for delivering peak loads as it can result in the power supply latching.

Fold forward

When the current drawn reaches the OCP limit, the voltage falls. This time the output current increases to a set maximum at short circuit.

Fold forward is well suited for powering up motors, but requires heavier system load cabling to handle the additional overload current.

Hiccup

At the OCP limit, the power supply turns off for a short interval and then automatically tries to restart. Hiccup mode reduces the need for heavy cabling or pcb traces, and this type of protection can be modified to deliver a peak load.

With traditional Analog Control though, the OCP points and recovery timing are fixed.

With Digital Control we can use software settings to adjust the limits and timing; for example we can set:

10s for an initial overload condition

60ms for heavy overloads

5ms for a short circuit condition with recovery times or 1 to 2 seconds

Let’s take an application example of a discharged capacitor bank being switched onto an operating power supply with Analog control.

The lower (blue) trace is the power supply current; restarting twice with the power supply current limit set at around 60A.

The top (gold) trace shows the output eventually recovering, but tolerances with the hiccup mode timing could have prevented a full recovery.

This time the same discharged capacitor bank is switched into a TDK-Lambda CFE400M supply incorporating digital control.

The blue trace is the current, gold trace is the output voltage

Using Digital Control, we can set the thresholds and timing accurately.

50A for 1.5ms (The short circuit condition)

30A for 50ms (The over current condition)

Notice that there are no multiple attempts to recover after the capacitor bank is applied to the power supply.

To summarize:

Digital control can allow for precise and repeatable current limiting using load dependant timing. We are not restricted to the value of a timing capacitor which can change due to:

a) Batch tolerances

b) Aging of the capacitor

c) Capacitor values changing with temperature

Digital control allows for easy tailoring for different applications with no physical modification of the power supply is needed. All changes are handled with software programming!

Tags: power_supplies, digital_control, constant_current, non-linear_loads

Higher Efficiency AC-DC Full-Brick Power Modules Have a Five Year Warranty

Nortski — Fri, 08 Oct 2021 07:52:17 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 7:52:17 AM

TDK Corporation introduces the TDK-Lambda PFE-SA series of AC-DC full brick power modules, representing a significant upgrade to the popular PFE-S series launched five years ago. These modules are particularly well-suited for outdoor and liquid cooled power systems, addressing the need for fan-less applications in the industrial, COTS and communications markets.

The new series achieves up to a 4% efficiency improvement (up to 91%) and has a five-year warranty. Like the existing models, the innovative PFE300SA, PFE500SA and PFE700SA bricks enable designers to utilize a single device containing power factor correction, regulation and input-output isolation.

Operating from a universal input of 85-265Vac (47-63Hz), the PFE300SA and PFE500SA models are available with nominal outputs of 12, 28 and 48Vdc (51Vdc for the semi-regulated PFE700SA model). All the power modules can deliver full power with an operating baseplate temperature range of -40 to +100^oC (-40 to +85^oC for the PFE500SA-12) in a 61 x 12.7 x 116.8mm package. In addition, over voltage, over current and over temperature protection is included.

The TDK-Lambda PFE-SA series is certified to the safety standards of UL/CSA/EN 60950-1 and is CE marked according to the Low Voltage and RoHS Directives.

More information can be obtained at the following TDK-Lambda Americas website, http://www.us.tdk-lambda.com/lp/products/pfea-series.htm, or by calling 800-LAMBDA-4. Product availability for the PFE-SA series can be found via the link to TDK-Lambda’s distributor network (see “Check Distributor Stock to Buy”) athttp://www.us.tdk-lambda.com/lp/.

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Major applications

Industrial, COTS (Commercial Off The Shelf), LED signage, test and measurement, broadcast and communications equipment.

Main features and benefits

Up to 91% efficient
Baseplate cooled
Five Year Warranty
Compatible with existing PFE-S modules (size, pin-out and specifications)

Major specifications

Model		PFE300SA	PFE500SA	PFE700SA
Input voltage range	Vac	85 to 265
Nominal output voltages	Vdc	12, 28 & 48	12, 28 & 48	54
Output power	W	300	396 - 504	714
Cooling	-	Conduction cooling via baseplate
Efficiency (200Vac Input)	%	85 - 89	86 – 90	91
Operating baseplate temperature	°C	-40°C to +100°C (PFE500SA-12: -40°C to +85°C)
Safety	-	UL/CSA/EN 60950-1, CE Mark (LV & RoHS Directives)
Size (W x H x D)	mm	61 x 12.7 x 116.8
Warranty	Years	Five

About TDK Corporation

TDK Corporation is a leading electronics company based in Tokyo, Japan. It was established in 1935 to commercialize ferrite, a key material in electronic and magnetic products. TDK's portfolio includes electronic components, modules and systems* marketed under the product brands TDK and EPCOS, power supplies, magnetic application products as well as energy devices, flash memory application devices, and others. TDK focuses on demanding markets in the areas of information and communication technology and consumer, automotive and industrial electronics. The company has a network of design and manufacturing locations and sales offices in Asia, Europe, and in North and South America. In fiscal 2013, TDK posted total sales of USD 9.1 billion and employed about 80,000 people worldwide.* The product portfolio includes ceramic, aluminum electrolytic and film capacitors, ferrites, inductors, high-frequency components such as surface acoustic wave (SAW) filter products and modules, piezo and protection components, and sensors.

About TDK-Lambda

TDK-Lambda Corporation, a group company of TDK Corporation, is a leading global power supply company providing highly reliable power supplies for industrial equipment worldwide. TDK-Lambda Corporation meets the various needs of customers with our entire range of activities, from research and development through to manufacturing, sales, and service with bases in five key areas, covering Japan, Europe, America, China, and Asia.For more details, please pay a visit to http://www.tdk-lambda.com/

Downloads

Editorial Contact:

David Norton VP Marketing
TDK-Lambda Americas Inc.
3055 Del Sol Blvd.
San Diego, CA 92154
Ph: 619-575-4400
Email: david.norton@us.tdk-lambda.com

Tags: communications, cots, industrial, ac-dc, broadcast, power_supplies, high_efficiency, led, tdk-lambda, signage, full_brick, brick, test_and_measurement

Reducing Switching Power Supply Radiated & Conducted EMI

Nortski — Fri, 08 Oct 2021 07:51:47 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 7:51:47 AM

One application issue that comes across my desk on a regular basis is where a customer has gone to an outside lab to certify their equipment for EMC, and they have failed conducted or radiated noise.

Usually the power supply in question is an open frame type, which does not have the shielding that a metal enclosed power supply has. There are two areas that are worth checking; grounding points and wire harnesses.

1. Grounding Points

Power supplies utilize decoupling capacitors; two are typically connected from input to earth ground (see below). Likewise, two are connected from the output to earth ground. This keeps the noise currents circulating close to the power supply, rather than allowing them to radiate around the end user’s system.

In an enclosed power supply these capacitors will be grounded through the metal case, but with an open frame type, it is up to the user to connect these points to ground. With the power density of products today, there often is more than one point on the power supply printed circuit board that needs to be connected. A common mistake is to only connect one, which can cause excessive radiated and conducted noise.

The installation manual will show which mounting holes / points need to be grounded. In the product below, three mounts should be connected (A, B & C).

The photo below shows the same power supply undergoing EMC testing, and it can be noted that the unit is connected to a metal plate with metal standoffs.

A quick glance of the underside of the printed circuit board will show which mounting holes have traces that need to be grounded. This smaller model has only one grounding point at the bottom right hand side of the board.

2. Wiring harnesses

In the test photo, it can be seen that the cable harnesses are neatly dressed and are kept away from the power supply. Wiring that is positioned above or below the unit will pick up radiated noise, thus defeating the purpose of having the EMI filter components.

If I am assisting customers on site, I always pack some tie-wraps in my tool kit to re-route any offending harnesses.

An earlier blog covers the standards http://power-topics.blogspot.com/2007/11/guide-to-emc-standards-for-power.html

Tags: radiated_emi, wiring_harnesses, emi, grounding_points, power_supply, conducted

HWS-A offers significant performance improvements to established HWS

Nortski — Fri, 08 Oct 2021 07:51:11 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 7:51:11 AM

TDK Corporation announces the introduction of the TDK-Lambda HWS-A series of AC-DC power supplies, comprising of five power levels rated from 15-150W. The HWS-A is a significant refresh of the established HWS series, which was originally introduced in 2005, and is completely form, fit and function compatible with the existing series to enable an easy upgrade.

The new series achieves up to a 3% efficiency improvement at full load (up to 91%), and up to a 4% improvement at low loads. Off-load power consumption is considerably reduced, thereby contributing to a reduction in environmental impact. Product weight has also been reduced by up to 12%.

Operating from a universal input of 85-265Vac (47-63Hz), the 15, 30, 50, 100 and 150W models are available with nominal outputs of 3.3, 5, 12, 15, 24 and 48Vdc. The 50, 100 and 150W HWS-A models include active power factor correction and all models are compliant EN61000-3-2. The operating temperature range is wider than its predecessor; from -10 to +50°C at full load, and up to 70°C with appropriate derating.

All models meet EN55011/EN55022 and FCC curve B requirements for conducted and radiated EMI and at high line input, the HWS-A meets the requirements of SEMI F47. The TDK-Lambda HWS-A series is approved to the safety standards of UL/CSA/EN 60950-1, UL508 (with cover), is CE marked according to the LV and RoHS Directives and comes with a limited lifetime warranty.

More information can be obtained at the following TDK-Lambda Americas website, http://www.us.tdk-lambda.com/lp/products/hwsa-series.htm, or by calling 800-LAMBDA-4. Product availability for the HWS-A series can be found via the link to TDK-Lambda’s distributor network (see “Check Distributor Stock to Buy”) athttp://www.us.tdk-lambda.com/lp/.

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Major applications

Industrial equipment used for factory automation, process control, LED signage, test and measurement, broadcast and communications

Main features and benefits

Up to 91% efficienct
Reduced off-load power consumption
Improved output derating with cover
Lighter weight

Major specifications

Model		HWS15A	HWS30A	HWS50A	HWS100A	HWS150A
Input voltage range	-	85 to 265vac (300vac for 5s), 120 to 370vdc
Nominal output voltages	Vdc	3.3, 5, 12, 15, 24 & 48V
Efficiency (200Vac Typical)	%	85%	88%	87%	89%	90%
Maximum output power	W	15W	30W	50W	100W	150W
Cooling	-	Convection cooling
Operating temperature	℃	-10 to +70℃ (with derating above 50℃)
Safety	-	UL/CSA/EN 60950-1, UL508 (with cover), CE Mark (LVD & RoHS)
Size (W x H x D)	mm	26.5×82×80	26.5×82×95	26.5×82×120	28×82×160	37×82×160
Warranty	-	Limited Lifetime

Tags: communications, hws, hws-a, broadcast, led_signage, factory_automation, and, power_supply, measurement, test_and, process_control

“Brute Force” Parallel of Power Supplies

Nortski — Fri, 08 Oct 2021 07:50:47 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 7:50:47 AM

You will see in many of our instruction manuals a warning about not connecting power supplies in parallel that do not have current share capabilities.

At first it would seem a nice easy way to get extra current. Take two like power supplies, connect them together and they will deliver twice the current?

Unfortunately there is a good chance that the two power supplies will not current share due to their output voltage set points. The power supply with the highest output voltage setting will deliver as much current as it can until it reaches its current limit threshold and then the output voltage starts to drop. The second power supply will then take over and provide the balance. The output voltage might glitch during the transition, affecting system operation.

For example, take two 24V 10A power supplies with an over current set point of 120% powering a 15A load:

Power supply A might deliver 12A (now at its current limit point)

Power supply B would then deliver 3A.

One could argue that the power supply is being protected by the current limit. There are two issues with this though:

1. A power supply is not designed to operate in current limit indefinitely. Internal temperatures will rise, reducing the life of the product
2. The safety certifications for UL, CSA are based on 100% load, not 120%

My recommendation is to use a power supply with a higher current rating, or choose one with a current share feature.

Tags: voltage, power_supply, current_share, limit

Quarter Brick DC-DC Converters have a 200-425VDC Input

Nortski — Fri, 08 Oct 2021 07:50:33 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 7:50:33 AM

TDK Corporation announces the introduction of the TDK-Lambda PH-A280 series
of DC-DC power modules with high voltage DC input. These quarter-brick modules
operate from a wide range DC input of 200 to 425VDC, which is widely used in
HVDC (High Voltage DC Current) and solar cell related applications.

The PH-A280 power modules are available in four output power levels of 50W,
75W, 100W and 150W. Nominal output voltages consist of 5V, 12V, 24V or 48Vdc;
adjustable by -20% to +10% (+/-20% for 5V output models). Efficiencies of up to
90% are achieved, an improvement of 5% over the prior series.

The modules can operate at full load over a wide baseplate temperature range
of -40 to +100°C making them suitable for liquid, air cooled or conduction
cooled systems. The dimensions follow the industry standard quarter brick
format (37.2 x 12.7 x 58.3mm).

As standard, the PH-A280 units are equipped with remote sense, remote on/off,
overvoltage and overcurrent protection circuitry and include TDK-Lambda’s 5-year
warranty. All models have an input-to-output isolation of 3kVAC, are
safety-approved to UL/CSA/EN60950-1 and carry the CE mark in accordance with the
LV Directive.

More information can be obtained at the following TDK-Lambda Americas
website, http://www.us.tdk-lambda.com/lp/products/pha-series.htm,
or by calling 800-LAMBDA-4. Product availability for the PH-A280 series can be
found via the link to TDK-Lambda’s distributor network (see “Check Distributor
Stock to Buy”) at http://www.us.tdk-lambda.com/lp/

Tags: dc-dc, compact, reliable, power_supply, brick

What Makes Switching Power Supplies Hiss

Nortski — Fri, 08 Oct 2021 07:50:21 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 7:50:21 AM

I attended a technical briefing two years ago given by one of our Product Managers on TDK-Lambda’s 400W CFE series, and was shown the various ways the product could potentially reduce internal energy losses - particularly at very light loads – using features available from the power supply’s digital control circuits. He did say that there were a couple of small side effects if all the features were enabled.

Recently one of our salespeople emailed me stating that in an off-load condition, his customer could hear a 10 kHz hissing sound coming from one of our 60W output power supplies and was curious if the unit was faulty. Normally I would have asked about capacitive loading conditions or if the product was being grounded correctly. Remembering the briefing I checked the product specification for no-load power draw. Seeing that it was a low 200mW, I talked to one of our Design Engineers.

Before Energy Star legislation came into force, power supplies would often draw 5, 10 or even 20 Watts when in a no-load condition. Apparently this was accounting for about four percent of the total electricity used in the US. Now most small power supplies will draw less than 300mW. Although the legislation is aimed at consumer products like phone chargers, many industrial customers are now requesting similar energy saving products.

I was informed that many of the new power supply control chips employ advanced energy saving features, and what my customer was hearing was probably the converter going into “burst-mode”.

AC-DC power supplies above 70W will often have two converters in them; one is the boost PFC (power factor correction) converter which ensures that the input current is not drawn in big “gulps”, but more sinusoidal like the applied AC voltage. An interleaved PFC converter shown below is used for this purpose.

The other is the main switching converter which chops up the high voltage DC from the PFC section and provides isolation, voltage step down regulation and filtering. A commonly used “half bridge” circuit is shown below.

Back to the subject of hissing! Without energy saving modes, both of these converters run continuously, regardless of the applied load. Each time the FETs switch, energy is used by the gate drive circuits and lost in parasitic inductance and capacitance.

To avoid this, designers of control ICs have implemented features where the power supply engineer can have the PFC converter, the main converter, or both converters turn off for short periods of time, aka “burst-mode”or pulse skipping, during light loading.

This means that instead of the FETs being turned on every 10us for a power supply operating at 100 kHz, the FETs will be switched on for a few cycles say every 100us. This is enough time to replenish the internal capacitors with energy and keep the output voltage in regulation.

The upside is much less power is dissipated in the power supply, but the downside is that instead of the product operating at 100 kHz (well above the human hearing range) a faint hissing might be audible as the burst mode operation operates at 10 kHz.

If the energy saving feature of the control IC is fully maximized, whereby a much longer interval between bursts is enabled, an increase in output ripple may be also observed. Often this is acceptable to the end user provided that the output voltage remains regulated.

My suggestion to the salesperson was to offer our customer an alternative power supply that had a slightly higher off load power draw, but no burst-mode operation. That suggestion was accepted.

Tags: draw, switching_power_supply, hiss, load

High Efficiency DIN Rail Mount Power Supplies Feature Compact Sizes

Nortski — Fri, 08 Oct 2021 07:49:27 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 7:49:27 AM

TDK Corporation announces the introduction of the TDK-Lambda DRB series of DIN rail power supplies for low power applications that require less space on the mounting rail.

Designed to support the growing trend for simple and economic DIN power solutions in industrial, building automation and process control applications, the DRB series combines low cost and extremely compact dimensions with industry leading efficiency of up to 91%. No load power consumption is between <0.3W and <0.5W depending on the model type.

“Customers are demanding DIN rail power supplies that can deliver high reliability in smaller packages” states David Norton, VP Marketing for TDK-Lambda Americas. “We believe that these are the smallest products of their kind on the market.”

Housed in a robust plastic case, the DRB series offer a narrow design, ranging from 18mm to 45mm, saving vital space on the DIN rail. The smallest model measures just 18mm x 75mm x 90mm (DRB15-24-1); all DRB models will mount on either a TS35/7.5 or TS35/15 DIN rail offering engineers a flexible option for various applications. In addition, they have been rigorously tested for shock and vibration while mounted onto the rail.

The supplies operate from a universal input of 85~264Vac and have EN61000-3-2 compliance, enabling worldwide use; moreover, they can withstand input voltage surges of 300Vac for 5 seconds. The DRB series is available with 4 output power levels ranging from 15 – 100W and nominal output voltages of 5V, 12-15V, 24-28V or 48Vdc.

The supplies can operate at full load over a wide temperature range of -10 to +55°C (+70°C for 15W model). Typical ripple and noise is below 40mV and a green LED indicates DC OK. Other features include over-current, over-voltage protection and a hold-up time of up to 20ms at 100Vac input voltage, full load.

The DRB series is approved to UL508 safety standard for industrial control equipment. Further safety approvals include IEC/EN 60950-1 (2nd Ed.) and UL/CSA 60950-1. CE marked in accordance with the LV Directive, EMC Directive and RoHS Directive, the power supplies are designed to meet EN55022 and CISPR22 Class B for conducted and radiated EMI, and come with a three-year warranty.

More information can be obtained at the following TDK-Lambda Americas website, http://www.us.tdk-lambda.com/lp/products/drb-series.htm, or by calling 800-LAMBDA-4. Product availability for the DRB series can be found via the link to TDK-Lambda’s distributor network (see “Check Distributor Stock to Buy”) at http://www.us.tdk-lambda.com/lp/.

Tags: compact, din_rail, 100w, drb, 48vdc, power_supply

Power Supply Filter Capacitor Values Can Change with the Applied Voltage

Nortski — Fri, 08 Oct 2021 07:49:09 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 7:49:09 AM

I read an article in one of the publications we advertise in recently where an Engineer had designed a timing circuit, but when he tested it, the frequency was too high. He rechecked his calculations and found out from the capacitor datasheet that the value of the particular multilayer ceramic capacitor he had chosen, changes with the applied voltage.

I did not pay much attention to it, being more involved with power supplies, until I was talking with one of our TDK-Lambda Engineers regarding non isolated POL (Point of Load) converters, and he gave me the same warning about the value selection of the filter capacitors. This is covered in the ceramic capacitor datasheets under DC Bias characteristics.

POL converters rely on quite large ceramic capacitors on the input and output to reduce the effect of the fast transient currents drawn by FPGAs, (which can cause the output voltage to deviate), with values sometimes approaching 2,000uF.

The concern our Engineer had was that our customers might not know about this. Intrigued I decided to investigate. Below is the DC-Bias Characteristic for a 22uF 16V multilayer ceramic capacitor.

If a capacitor value of 22uF was recommended by the application note for filtering the 12V input voltage on a non-isolated converter and the user picked this particular part, in actuality, the real capacitance would be closer to 12uF.

Upon testing the filtering, the user might complain that the application note was incorrect, whereas in fact the capacitor datasheet had not been interpreted correctly.

Something to bear in mind!

Tags: capacitor, appied_voltage, power_supply, filter

Applications of DC-DC converters For Base Station RF Power Amplifiers

Nortski — Fri, 08 Oct 2021 07:48:21 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 7:48:21 AM

When a DC-DC converter is in proximity to the Power Amplifier (PA) in an RF transmitter, regardless of whether it is located at the top or at the base of the antenna tower, the switching action of the converter is a potential source of RF interference. Many features of TDK-Lambda’s PAH450S series of power modules provide safeguards against this. For example, the sealed casting of this module effectively acts as a containment shield for radiated EMI generated by the converter that could be sensed and amplified by the RF PA. Conducted EMI is also a concern, with the chief sources being conducted EMI from the converter input back onto the supply bus, and voltage ripple on the converter’s output being coupled into the PA.

To suppress conducted EMI, RF Power Amplifier customers generally design their own input filters. Guidelines for conducted emissions standards generally stop at 30 MHz, while the typical frequency range for the PAs is between 800 MHz to 2 GHz. Therefore, these standards are mainly directed at guarding against potential interference with other RF equipment sharing the PA’s power bus. This precaution can be compared to warning pacemaker patients about staying away from microwave ovens; the risk may be slight, but the consequences can be drastic.

The compact size (half brick) of TDK-Lambda’s PAH450S dc-dc converter provides a high power density suitable for driving analog PAs in integrated modules for base-station applications.

Regarding external interference, as well as the potential interference from the converter’s output voltage ripple, while general guidelines are applied to prevent RF interference, this risk is also minimized by the fact that the RF and power converter frequency domains are significantly different. Therefore, with careful design practices, RF interference from the converter is not a major concern, though as converter’s switching frequencies increase it may become a significant design issue.

In addition, thermal issues represent a significant challenge in the design of transmitters, especially in a combined PA/converter module. In configurations where the converter and the RF PA are co-packaged as a single module and installed at the top of the tower (alternative configurations keep the complete RF transmit stage at the base of the tower), even modest gains in efficiency can have tremendous performance advantages.

For example, an improvement in converter efficiency from 90% to 92% can lead to total heat reductions of up to 20% in the combined module. The less heat produced by the converter, the more RF output power that can be generated by Power Amplifier, which is usually the driving parameter for the transmit path.

Packaged in a standard half-brick case, these DC-DC converters are available with 28V or 48V outputs, and reach efficiencies up to 92%. Digital power control might seem to hold the potential to introduce further single-digit percentages in gained efficiency. However, our customer’s tell us, to emulate the equivalent operation of an analog control loop operating at 1MHz (for example), the clocking frequency of a digital controller would have to be significantly higher, which could then hasten the arrival of higher RF interferences with the RF PA in future systems.

Other advances, mainly in RF power device technologies such as SiC and GaN semiconductors, will have a greater impact on the overall efficiency of transmitters than digital power control. For now, converters with analog control such as the PAH450S series represent a solid option for powering analog PAs.

Power supplies needed for the PAs of next-generation base station applications are also faced with several other requirements. These include the ability to withstand extreme ambient temperature swings, compact size, and a wide output adjustment range to allow the user to optimize the amplifier’s performance. TDK-Lambda’s PAH450S series of 450 W dc-dc converter modules are designed to meet these demands. For example, many cell repeaters are configured as three separate single-pole antennas, each 2 ft to 3 ft tall, mounted in a triangular configuration on a 200 ft to 300 ft tower. Each pole typically has a separate RF PA and dc-dc converter. A power bus is routed up the tower, and the wide input range spanned by the 48V version of the converter (36V to 76Vdc) is highly tolerant of the voltage drop that can occur along the length of the power bus, which can range from 6V to 7Vdc.

Tags: dc/dc, amplifier, half_brick, 450w, rf, base_station, antenna

Compact, Low-Voltage Power Supplies Suit Many Applications

Nortski — Fri, 08 Oct 2021 07:47:26 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 7:47:26 AM

TDK Corporation announces the extension of the TDK-Lambda GWS500 series power supplies with the addition of two low output voltage models. Combining the same high efficiency, high power density and low standby power characteristics as other models within the GWS500 series, the 5V 80A and 7.5V 67A models are well-suited for fitting into 1U enclosures. The GWS series is a 400W to 500W ac-dc, forced air-cooled power supply that achieves up to 90% efficiency, dramatically cutting the heat generated in industrial, LED, display/signage, IT, traffic controls, automated service, kiosks, test & measurement, and audio/video applications.

Featuring a 4.1 x 8.6 inch footprint and 1.6 inch height, the GWS500 is one of the smallest products in its class. This series is now offered in six models with nominal outputs of 5V, 7.5V, 12V, 24V, 36V and 48V. To accommodate non-standard system voltages the GWS500's output is user-adjustable, either via the built-in adjustment potentiometer or by injecting an external programming voltage. Where peak power is needed, for example for motor start-up, the 24V and 36V models can deliver up to 600W for 10 seconds. The supply can be operated at full load from -25 to +50°C ambient temperature and up to +70°C with suitable derating.

These power supplies include overvoltage, overtemperature and overcurrent protections. Also included are 5V/0.3A standby output, remote on/off, and DC Good signal, as standard.

The GWS500 operates from 85 – 264VAC, is UL/EN/IEC 60950-1 safety certified (2nd Edition) and carries the CE mark. All models meet EN61000-4-X immunity and EN61000-3-2 harmonic correction standards.

The TDK-Lambda GWS500 series is available in stock for immediate sale.

More information can be obtained at the following TDK-Lambda Americas website, /lp/products/gws-series.htm, or by calling 800-LAMBDA-4. Product availability for the GWS500 series can be found via the link to TDK-Lambda’s distributor network (see “Check Distributor Stock to Buy”) at http://www.us.tdk-lambda.com/lp/.

A wide range of additional TDK-Lambda AC-DC power supplies and DC-DC converters can be viewed at this website: http://www.us.tdk-lambda.com/lp.

Tags: 500w, automated_service, audio, industrial, video, kiosks, test_&_measurement, led, signage, new_product, gws, display, it, traffic_controls

What Size Heatsink Do I Need?

Nortski — Fri, 08 Oct 2021 07:46:56 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 7:46:56 AM

Today there are a large array of high power modules in the range of 300 to 1,000-watts, both DC-DC converters as well as AC-DC power modules, which are commonly referred to as “bricks.” Even though these devices feature high conversion efficiencies in the area of 85 to 90% (or higher), some power is lost in the form of heat that must be dealt with in order to maximize the lifespan of the end product. For example, a 500-watt power module with 90% conversion efficiency would generate over 55-watts of wasted heat within the module that must be removed to maximize its reliability.

The concentrated power density (watts per cubic inch) within these power modules make them a challenge to cool in real world applications. Most high power bricks are packaged in thermally conductive plastic or epoxy cases with integral metal baseplates. The high power components within the bricks (i.e., semiconductors, inductors, transformers, etc.) are thermally coupled to these baseplates, which in turn can be attached to external heatsinks or liquid-cooled cold plates in order to keep the baseplate at or below its maximum operating temperature (typically 85 to 100°C).

The maximum baseplate temperature is primarily determined by the maximum internal junction temperature of the semiconductors within the power bricks. The term “thermal management” refers to the designer’s challenge of cooling these power bricks by considering the many levels for heat transfers via conduction (direct contact between solids), convection (contact with air or a fluid) and thermal radiation (electromagnetic infrared energy), both internal and external to the power module.

The diagram above shows the series-connected thermal resistances that impede the flow of heat from one level to the next. These impedances need to be considered, beginning with the internal semiconductor’s junction temperature relative to its case, the thermoplastic module case and its metal baseplate, and ending with a mechanically attached heatsink that conducts away the heat from the baseplate to the surrounding ambient air via natural or forced air convection cooling. Heatsinks are designed to cross thermal barriers primarily by substantially increasing the surface area that comes in contact with the ambient air, thereby providing enhanced convection cooling. Because the mating surfaces of the power module’s baseplates and heatsinks are not perfectly flat, some type of thermally conductive interface material is required to fill the tiny voids. This interface material can range from a thin layer of thermal grease to a custom designed silicon pad.

AC-DC Power Module with Heatsink & Other Components

Selecting the proper size and shape of a heatsink and determining if forced air cooling is required are among the tradeoffs the designer needs to consider. This process begins with a detailed review of the power module’s specifications and knowledge of the end product’s heat loads, internal and external operating temperatures, space constraints, and available air flow sources, paths and restrictions.

The next step in this process is to determine the amount of power that will be lost (wasted) within the power module, based on its efficiency. This information for computing this is usually listed on the power module’s datasheet or installation manual, but it can also be determined by actual measurements of the input and output powers. For this example, we will use a typical AC-DC power module with a 48V/10.5A, 504W output rating, and a typical efficiency of 85% with a 120VAC input. By the way, the 85% efficiency rating is very good considering the fact that this module contains full-bridge rectification and active power factor correction AC front-end circuits as well as an integral DC to DC converter. In addition, this module has a maximum operating baseplate temperature, as measured at its center point, of 100°C.

Based on the above information, to compute the internal power dissipated (wasted heat); we can use the following formula:

Pd = (Pout / η) – Pout

Definitions & Calculation Example:

Pd : Internal Power Dissipated (W)

Pout : Output Power (504W)

η : Efficiency (85%)

Pd = (504W / 0.85) - 504W = 88.9W

To calculate the required baseplate to ambient air thermal resistance that would be needed for this application, the following formula would apply:

θba = Tb - Ta / Pd

Definitions & Calculation Example:

θba : Baseplate to Ambient Air Thermal Resistance (°C/W)

Tb : Baseplate Temperature (100°C)

Ta : Ambient Air Temperature (40°C)

Pd : Internal Power Dissipated (88.9W)

θba = 100°C - 40°C / 88.9W = 0.67°C/W

In this example, we would need a heatsink (with or without air flow) that provided a thermal resistance of 0.67°C/W. However, unless the heatsink includes a thermal interface material like thermal grease or a pad in its rating, we need to account for this additional thermal contact resistance (θbs), which can be on the order of 0.1°C/W. Therefore, the required thermal resistance of the heatsink itself, with the thermal interface material included, can be calculated per this formula and example:

θba-bs = θba – θbs

θba – θbs = 0.67°C/W - 0.1°C/W = 0.57°C/W

The next step in this process is to review specifications for potential heatsinks that have a thermal resistance of 0.57°C/W. In this case, the power module has three optional heatsinks to choose from as shown in the chart below.

The Y axis of this chart shows the thermal resistance between the heatsink and the air (°C/W) and the X axis shows the required airflow velocity for the three heatsinks. In this example, we need to find 0.57°C/W along the Y axis and then move to right along the X axis to where it intersects a heatsink curve. In this example, 0.57°C/W intersects with the HAF-15T heatsink curve at about the 1 m/s airflow velocity point. Therefore, for this application we would select the model HAF-15T heatsink and would have to provide forced air cooling with an air velocity of 1 m/s. To translate m/s (meters/second) into LFM (linear feet/second), use this general conversion factor: 1 m/s = 200 LFM. In this example, since 1 m/s = 200 LFM of forced-air velocity, the fan required for this application must provide 200 LFM.

Based on the above, we have now determined the requirements for cooling this power module with a heatsink, thermal compound and forced air flow. If we wanted to be more conservative and improve the MTBF of the module, we would recalculate the required heatsink with the assumption that we wanted to keep the baseplate temperature at 85°C.

A word or caution should to be injected here. After going through the thermal calculations and selecting a heatsink, air flow, etc., the next step is to confirm the “paper-design” by running actual tests on a sample unit. The tricky part is to get access to the center point of the power module’s baseplate so you can measure the temperature at that point while the module is operating under load. One way to do this is to drill a hole in the center of the heatsink so the leads from a thermocouple can be mounted on the module’s baseplate and routed to your temperature measurement device.

In summary, we have shown how to determine the correct heatsink for power module applications. As the efficiencies of these devices improve the need for cooling will reduce, but the designer should always be aware of the heating effects from not only from the power module, but also from nearby devices. Therefore, it’s always best to run actual thermal tests with thermocouples attached to the power module and inside the end product to insure the design will be as reliable as possible.

Tags: heatsink, temperature, power_supply, thermal, brick

New 250W Convection-Cooled Power Supply Features Low Profile, High Efficiency and Wide AC Input Range

Nortski — Fri, 08 Oct 2021 05:48:44 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 5:48:44 AM

TDK Corporation announces the release of TDK-Lambda's new CUS250LD series low profile AC-DC power supplies. These single-output supplies provide 250-watts of output power with convection cooling (no fans required). This design eliminates the need for fan maintenance and reduces acoustic noise and vibrations. In addition, they feature a low profile of only 1.18" and a compact footprint of 4.0" x 7.8", making them an ideal choice for applications in light industrial, LED signage, communications, broadcast, gaming, point-of-sale, IT, and test & measurement equipment.

The supplies operate from a universal input of 85-264Vac, 47-63Hz, with PFC, enabling them to be used anywhere in the world. Moreover, they can operate from a 120-370Vdc input. These units have an input- to-output withstand voltage of 3kVac. The CUS250LD series are available with an output voltage of 3.3V, 4.2V, 5V, 12V, or 24Vdc, all of which have a +/-10% user-adjustment range.

The convection-cooled operating temperature range is from -25°C to +70°C with derating above +40°C. The power-saving efficiency is up to 90%. Other standard features include overvoltage and overcurrent protections plus a green LED indicator that is lit when the supply is on.

The CUS250LD series feature global ITE and general purpose safety agency certifications per UL/CSA/EN60950-1, EN50178, and are CE Marked. The supplies meet the conducted and radiated EMI requirements of EN55022-B & FCC Class B and include a three (3) year warranty.

More information about the CUS250LD is available at TDK-Lambda Americas' website: http://www.us.tdk-lambda.com/lp/products/cus-series.htm , or by calling 1-800-LAMBDA-4.

Product availability for the CUS250LD series can be found via the link to TDK-Lambda's distributor network “Check Distributor Stock to Buy" at: http://www.us.tdk-lambda.com/lp/ .

A wide range of additional TDK-Lambda AC-DC power supplies and DC-DC converters can be viewed at this website: http://www.us.tdk-lambda.com/lp

Tags: 250_watt, cus250, single_output, convection_cooled

Power Supply "Remote Sense" Mistakes and Remedies

Nortski — Fri, 08 Oct 2021 05:43:48 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 5:43:48 AM

Most medium to high power AC-DC power supplies and some DC-DC converters include "Remote Sense" connection points (+ and - Sense) that are used to tightly regulate the supply's output voltage at the load. Since the output cables that connect a power supply's output to its load have some resistance, as current flow increases, so will the voltage drop across the cables (I x R = Voltage Drop). Moreover, since it's best to regulate the voltage directly at the load, the use of the two Remote Sense wires connected from the supply to the load will compensate for these unwanted voltage drops. Refer to Fig. 1 which shows the typical connections when the Remote Sense function is used.

Fig. 1: Power Supply with Twisted "Remote Sense" Wires Connected to the Load

Typical "Remote Sense" Problems & Remedies

Most remote sensing circuits are capable of compensating for from 0.25V to 0.75V of voltage-drops across the output cables. However, to be sure, always check your power supply's instruction manual to determine its maximum remote sense compensating range. If the voltage drop across the output cables exceeds the compensating range of the remote sense circuits, the voltage at the load will no longer be regulated. This problem can be remedied by either reducing the length of the output cables or increasing the size (heavier wire gauge) of the output cable's to reduce the excessive voltage drop. Voltage drops across the output cables should be minimized since this is a source of wasted power. For example, with just a 0.5V cable drop with a 100A load, the lost power amounts to 50W in each cable or 100W total.
The remote sense function automatically increases the output voltage at the output terminals of the supply to compensate for any unwanted voltage drop in the output cables with heavy load currents. Likewise, the remote sense function decreases the output voltage of the supply when the required load current is reduced. In some applications, the power supply's output needs to be adjusted by the user to voltage higher than its nominal (e.g. 5V nominal, adjusted to 5.5V). Always adjust the power supply's output while measuring the voltage at the load. In addition, care should be taken to assure that under full load that the remote sense function does not push the Vout to a higher voltage that could possibly trip the OVP set-point and shutdown the supply. Therefore, always read the power supply's instruction manual to be aware of the supply's adjustment range and OVP set-point.
The remote sense leads carry very little current so light gauge wires can be used. However, steps should be taken to ensure that the remote sense wires do not pick up radiated noise by either twisting the + and - Sense wires together and/or by shielding the wires from the noise (refer to Fig 1). It is best to use different colored sense wires (e.g., black and red) so that after they are twisted it is easy to determine which wire is the + and – Sense.
Refer to Fig. 2 below for a simplified schematic of a power supply's remote sense circuits. It is important to observe the correct polarities, i.e., the +Sense wire should connect at the load near the +Vload connection and the –Sense wire should connect at the load near to the – Vload connection. If by mistake the remote sense wires are crossed-connected (+Sense to –Vload and – Sense to +Vload) current will flow in the Sense lines and burn out the internal Rsense resistors, causing a malfunction of the supply. Typically, these internal Rsense resistors are around 10 to 100 Ohms with a maximum rating of 0.5W.

Fig. 2: Simplified Schematic of Remote Sense Circuit with External Output & Sense Wires

We have seen applications where the user has installed a switch or fuse in series with one or both output wires. This can cause a serious problem if the remote sense lines remain connected to the load, because if the output cable switch or fuse opens, current will flow in the sense lines and cause the internal Rsense resistors to burn up. System debugging can cause similar problems, for example, where the power and sense cables are located on separate connectors and if by error, only the power cable connector is disconnected.
There are applications where the user may not want to use the remote sense feature. In these cases, the remote sense lines should not be left open for optimum load regulation; instead, a local sense configuration must be used. Referring to Fig. 3, to use a local sense set up the + and -Sense lines should be connected to either their corresponding local sense (LS) terminals, which are provided on many power supplies, or connected to the corresponding +Vout and –Vout terminals. Most power supplies are shipped from the factory with these "Local Sense" jumpers installed on the power supply (see photos below).

Fig. 3: Schematic of Power Supply with "Local Sense" Jumpers Installed

Photo of Power Supply with Local Sense Wires Connected (see Red & Black jumper wires)

Photo of PSU with Sense Screw Terminals Connected to Output Screw Terminals with Metal Jumpers

In summary, the "Remote Sense" feature automatically compensates for unwanted output cable drops, which vary as the output current increases and decreases. This feature is advantageous to the user, but is subject to mistakes that should be avoided to insure the proper operation of the power supply and the end-product.

Ultra Compact 800-Watt Programmable Power Supply Features Advanced Digital Controls

Nortski — Fri, 08 Oct 2021 05:34:50 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 5:34:50 AM

TDK Corporation announces the expansion of TDK-Lambda's Z+ Series of programmable power supplies, which now includes the new 800-watt models in addition to the previously released 200, 400 and 600-watt models. These high-density, high efficiency, 2U format, bench-top and rack mountable power supplies are designed to meet the demands of a wide variety of ATE, Laboratory and OEM applications, including: Test & Measurement, Semiconductor Burn-in, Component Test, LED/Laser Test, RF Amplifiers, Electromagnetic, and Electrochemical applications.

TDK-Lambda's new Z+800 provide 800-watts of output power with a selection of output voltage ranges that cover from 0 to 100Vdc with output currents up to 72A. The Z+ 800W are 66% smaller and 67% lighter than previous generations and similar products, and provide a 200% increase in power density. All Z+ standard models are only 3.27" high by 2.76" wide, so up to 6 units can be installed in the optional 19" rack housing and blanking plates are available for unused slots.

The Z+ 200W, 400W, 600W and 800W programmable power supplies have comprehensive front panel controls with individual rotary encoders for output current and voltage, and access to power supply settings such as OVP level, start-up modes, remote control and monitoring parameters. Separate 4-digit volt and current displays are provided along with function/status LEDs, pushbuttons for output preview, output on/off, fine/coarse and other features. Options for front panel output-jacks and multiple-unit housings are available for bench-top applications. Later this year the 600W models will be added to the Z+ Series.

All Z+ models include built-in arbitrary waveform generation and storage for up to 4 pre-programmed functions; making them ideal for test and simulation tasks in the Automotive, Solar Panel and LED/Laser industries, to name a few. These power supplies feature very fast command processing times, output sequencing and two programmable output pins that, for example, can be used to control isolation relays. Up to 12 voltage or current values can be programmed using the waveform creator software provided and 4 wave-forms can be stored in the Z+ unit's memory. More complex waveforms can be created using LabView. These waveforms can be either repetitive or single-shot and injected into the system under test. The results can be analyzed confirming the proper or faulty operation of the powered device or system.

All models within the Z+ Series can operate in a constant-current or constant-voltage mode from a wide 85 to 265Vac input. They feature active power factor correction, variable speed fans and extensive safety features including user-selectable Safe-Start and Auto-Re-Start. With Safe-Start, the power supply returns to the last used settings after a power interruption, but with the output disabled. With Auto-Re-Start, the supply resumes normal operation without intervention after a power interruption, thereby meeting typical requirements for unattended use.

Common to all Z+ models are the built-in USB, RS232 and RS485 interfaces. Using the standard serial RS485 interface between units enables daisy chain control of up to 31 power supplies on the same bus.

Analog remote programming and monitoring is user selectable from 0-5V or 0-10V. Other digital and isolated analog interfaces are optional. The GPIB interface is IEEE-488.2 SCPI compliant and multi-drop (only one unit needs the IEEE interface, which can then feed the commands to others via RS485). LabView and LabWindows drivers are also available. Isolated analog programming and monitoring options include either 0-5V or 0-10V, and 4-20mA control. An LXI Class C compliant LAN interface is also available.

Higher power systems can be achieved by connecting up to 6 identical units in parallel with active current sharing. When connected as a master/slave parallel configuration, the master unit reports total system output current, which means that up to 6 units appear as a single power supply to the remote controller, thereby simplifying operations. Up to 2 units may be connected in series to increase the output voltage or to provide a bipolar output. CE marked in accordance with the Low Voltage Directive, the Z+ Series con-form to the conducted and radiated EMI specs per EN55022-B, FCC part-15-B, and VCCI-B. Safety certifications include UL-, EN- and IEC61010-1, plus these units are designed to meet UL/EN60950-1. All models carry a five (5) year warranty.

Tags: test_and_measurement_equipment, z+, digital_control, 800w

What does SELV mean for Power Supplies?

Nortski — Fri, 08 Oct 2021 05:33:34 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 5:33:34 AM

SELV stands for Safety Extra Low Voltage. Some AC-DC power supply installation manuals contain warnings concerning SELV. For example, there may be a warning about connecting two outputs in series because the resulting higher voltage may exceed the defined SELV safe level, which is less than or equal to 60VDC. In addition, there may be warnings about protecting the output terminals and other accessible conductors in the power supply with covers to prevent them from being touched by operating personnel or accidently shorted by a dropped tool, etc.

UL 60950-1 states that a SELV circuit is a “secondary circuit which is so designed and protected that under normal and single fault conditions, its voltages do not exceed a safe value.” A “secondary circuit” has no direct connection to the primary power (AC mains) and derives its power via a transformer, converter or equivalent isolation device.

Most switchmode low voltage AC-DC power supplies with outputs up to 48VDC meet the SELV requirements. With a 48V output the OVP setting can be up to 120% of nominal, which would allow the output to reach 57.6V before the power supply shuts down; this would still conform to the maximum 60VDC for SELV power.

In addition, an SELV output is achieved through electrical isolation with double or reinforced insulation between the primary and secondary side of the transformers. Moreover, to meet SELV specifications, the voltage between any two accessible parts/conductors or between a single accessible part/conductor and earth must not exceed a safe value, which is defined as 42.4 VAC peak or 60VDC for no longer than 200 ms during normal operation. Under a single fault condition, these limits are allowed to go higher to 71VAC peak or 120VDC for no longer than 20 ms.

Don’t be surprised if you find other electrical specs that define SELV differently. The above definitions/descriptions refer to SELV as defined by UL 60950-1 and other associated specs regarding low voltage power supplies.

New 400W Quarter Brick Converters Feature 95% Efficiency in Standard DOSA Footprint

Nortski — Fri, 08 Oct 2021 05:33:08 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 5:33:08 AM

TDK Corporation announces the new TDK-Lambda iQG Series of DC-DC converters that are ideal for intermediate or distributed bus power architectures. Featuring a low profile package that is only 0.52 inch high, these converters have been designed with confined space and demanding thermal environments in mind for applications such as Datacom/Telecom, Wireless/Broadcast, Robotics, Industrial Controls and Test & Measurement. The iQG series provides a regulated 12VDC output with a high-isolation of 1500VDC, input to output. In addition, they operate with a wide input range from 36V to 75VDC. The user can select from models rated at 300W or 400W, depending upon their needs.

The converter's efficiencies of up to 95% substantially minimize wasted heat and system cooling issues. Throughout the open frame, single board construction, particular attention has been made to the overall thermal design including component height, location and orientation. As a result, the iQG Series is compatible with all cooling strategies, including conduction, convection and forced air, and offers outstanding thermal performance for cooler operation over its operating baseplate temperature range of -40 to +125°C. Furthermore, the proprietary TDK ASIC control circuitry brings a significant component count reduction, as well as improved reliability and lower cost.

The monotonic start-up into a pre-bias output capability with its synchronous rectification enhances the converter's versatility. Standard features include fixed frequency operation, remote on/off, and auto-recovery protection against input under voltage and output over current and over temperature.

The iQG 400W units have an impressive 230W per cubic inch power density and deliver up to 33A of useable output current. The 400W models can be used individually or units can be connected in parallel for higher power applications.

Safety approvals for the iQG series include UL60950-1 (US and Canada), VDE 0805, CB scheme (IEC60950-1), and the CE Mark. These converters are available now and economically priced at $59.00 each in 100 piece quantities.

Tags: distributed_bus, efficient, 400w, thermal_environments, low_profile

Power Supply Rise and Fall Output Characteristics

Nortski — Fri, 08 Oct 2021 05:33:02 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 5:33:02 AM

A common question asked by our customers is “what are the power supply’s rise and fall output characteristics?” Our usual answer “it depends” sometimes raises an eyebrow. Let’s have a look at why.

As you know, there are two ways a power supply can be turned-on and off. One method is to apply or remove the AC input power via a switch or circuit breaker to the supply. Another method is use the Remote On/Off control of the supply, if the unit has this feature. Let’s examine both methods.

The curves below (Fig. 1) show the typical delay between when the AC input power (Vin) is applied and the power supply’s output reaches its rated voltage of 12V under full load conditions. As can be seen (in this example) with a low AC input of 85VAC the output turn-on delay is slightly more than with higher input voltages. However, in this example, the typical turn-on delay is about 250ms and the output rise time is about 25ms.

Conditions:

Vin	: 85VAC (A)
	: 115VAC (B)
	: 230VAC (C)
	: 264VAC (D)
lout	: 100%
Ta	: 25°C

Fig. 1

The next curves (Fig. 2) show the same power supply’s output (with 100% load) when the AC input is removed. The time delay from when the AC power is removed (or lost) is referred to as the Hold-Up time spec. For this supply, the specified minimum hold-up time is 16ms. As shown below, the measured hold-up time is about 30ms, which meets the spec. The output fall time is approximately 10ms, when measured from 90% to 10%. Note that the energy is pulled from the power supply very quickly due to the heavy load on its output.

Fig. 2

By comparison, without a load (zero load), the curves below (Fig. 3) show that the Hold-Up time of the power supply increases substantially to about 1.8 seconds, and the output drops to zero in about 6 seconds!

Fig. 3

Below is a graph (Fig. 4) for this power supply that shows how minimum Hold-Up time varies as the load changes between 10% and 100% (maximum load).

Fig. 4

Next, we shall review how the remote on/off control (if used) can affect the power supply’s output rise/fall, and delay times.

Conditions:

Vin	: 115VAC (A)
lout	: 100%
Ta	: 25°C

Fig. 5

In the above curves (Fig. 5), the remote On/Off control is the bottom trace and above that is the power supply’s DC OK signal level. This situation assumes the AC input in always on. As can be seen, from the time the Remote On is activated (goes from high to low logic level); it takes the output about 150ms to reach its full rated voltage. And, the DC OK signal changes state when the output level is about 75% of its rated voltage, which in this case is about 125ms after the Remote On signal is activated.

The next set of curves (Fig. 6) show the reverse situation, where the Remote On/Off signal is used to turn the power supply off.

Fig. 6

There is about 25ms delay after the Remote On/Off changes state to when the Vout reduces to approximately 75% its nominal. In addition, at that time the DC OK signal changes state. The output fall time, from 90% to 10% of nominal, is approximately 15ms.

From the above curves and explanations, I believe the reader can see why our answer at the beginning was "it depends." In these types of measurements, delay times are in many cases more important than rise and fall times. Other considerations include the AC input voltage, the load, operating temperatures, measurement criteria and the design specifications for the power supply.

Tags: fall, on/off, rise, remote

New 1600 Watt Power Supply Features 92% Efficiency with Digital Controls

Nortski — Fri, 08 Oct 2021 05:32:55 GMT

Current Revision posted to Documents by Nortski on 10/8/2021 5:32:55 AM

TDK Corporation announces the new TDK-Lambda RFE1600 Series; a 1600W single-output AC-DC power supply in a low profile package (less than 1U high) for stand alone or distributed power architectures (DPA). These supplies are ideal for applications requiring reliable 12V, 24V or 48VDC bulk power. The output voltage is user adjustable enabling the RFE1600 to be used in a variety of customized applications.

Operating efficiencies of up to 92% minimizes wasted heat dissipation and system cooling issues. Featuring a universal input of 85 to 265VAC with PFC, typical applications for the RFE1600 supplies include communications, factory automation, test/measurement, robotics and broadcast/RF amplifiers. Models with a "/S" suffix include the optional I²C/PMBus serial communications port for remote control and monitoring.

These supplies can be used individually or up to 10 units can be connected in parallel for high power or N+1 redundant power systems, facilitated via built-in ORing FETs and active current share ports. Each power supply has two variable-speed cooling fans and the supplies can operate in temperatures ranging from -10 to +70°C. The RFE1600 has a high power density of 23.5W/in³ with dimensions of 12.6 x 3.35 x 1.61 inches.

Overvoltage, overcurrent and overtemperature protection are standard features, and for system monitoring there are opto-isolated signals for DC-OK and AC-fail, along with a LED indicators for DC-OK or Fail conditions. Remote On/Off control is standard as is an auxiliary 12V/0.5A output.

As well as being EN55022 and FCC EMC compliant (achieving class B conducted, and Class A radiated emissions), the RFE1600 series are certified to UL/EN 60950-1, 2nd Edition, safety requirements and carries the CE Mark. Harmonic correction meets the EN61000-3-2 standard and the power supplies are backed by a three-year (3 yr) factory warranty.

Tags: 1600_watt, distributed_power_systems, digital_control, efficiency, rfe1600