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Pre review : EXAR (Digital Power Studio) XRP7714

Former Member

Hi all,

 

Just receive today the EXAR XRP7714ILB-FXRP7714ILB-F board.

It's just a pre review, I'm waiting the webinar to have more information on this product.

 

Technical content.

 

I receive the package, composed by one boart XRP7714EVB, one power supply for tests, one USB Cable and one USB key.

 

image

 

First, "RTFM" image, insert the 2G USB key into the computer.There is 10 PDF files, product datasheet, Quick start guide and one folder for installation program.

No worries during software installation on Windows Seven 64 bits, but the USB driver seems not to be compatible with this operation system.


Perhaps did I check if a newer version is released on the web. I just have completed registration, but I have to wait to have access to secure ressources.

 

Fine, my account have just be validated by exar. There is an updated version of software and driver. Also, all is running well on Windows Seven 64 bits

 

So, a little view on the bord

 

image

 

Nice board, you can also use the furnished power supply (12V 1600mA) or connect your own power supply, respecting specifications.

 

Next to come after webinar ...

 

I don't like to stay on install problem. I also install software on my notebook, running Windows Seven 32 bits. Install running well.

To install the USB driver (seen as an serial com), just right click on Computer, select "Manage" (translating from French menu) and select "Device Manager"

Click on the Exar line, Udpate the driver with manual installation.

 

Finally, launch "Digital Power Studio" and check the board detection.

  • Hi Eric,

     

    I joined the Power XR webinar yesterday.

     

    I will write down my experience on the XRP7714EVB.

     

    My RoadTest package came complete with software, power supply, cables and EVB. It was plug and play. During the Webinar of yesterday i noticed that there was a new software (power studio) release V3. The biggest advantage is the reading of the OCP setting and actual output current reading. In my version it was still measured voltage drop across a FET and maximum voltage drop across a FET. You have to calculate the current by the nominal Rds(on) given by the datasheet of the used FET.

     

    I noticed that changing a setting during an 'automatic update' was sometimes difficult. I therefore disabled the 'automatic update' during changing of setting to avoid mistakes.

     

    Loading the outputs with 3A was no problem. A high Vin/Vout ratio gives a poor efficiency (80%), but if the ratio is under control the efficiency is about 90%. Test: Output 5V/3A, Input: 7.6V/2.2A. The ripple and noise in that condition was only 20mVp-p @300kHz switching frequency and even 10mVp-p @ 400kHz.

     

    During the webinar i placed a remark that the OCP is pretty fast. If you switch a capacitive load (> 100uF) the output current will likely be higher than your predefined setting and trip a protection. Result: controller shutting down for 200ms. You have to be careful those load transients. I normally give an OCP and timing dependent characteristic (high current surges for short times are allowed).

     

    De OTP is measuring the controller temperature. This is the ambient temperature measurement of the circuit board and not the hottest part in the design. The buck coil will be the hottest part or the mosfets. Anyway, the OCP setting will prevent the circuit from overheating.

     

    The OCP setting is temperature dependent. This is normal when the Rds(on) is used to measure the output current. If a current sense resistor is used this is more temperature-independent, but the efficiency goes down and the component count is higher.

     

    An important remark: you can not parallel outputs to boost the output current. A so-called interleaved Buck Converter. The control loop is not designed for that. You need current control and a master/slave(s) configuration.

     

    My general conclusion is that the availability of devices like this will create a demand for more intelligent power modules. Knowing whet the status of the power rails are is becoming increasingly important: are there warnings on current, voltage, temperature? Are there any faults? Power good feedback and several other features. I also like the turn-on and off timing control and the ability to set the phase of the switchers.

     

    The use of this device in a more complex power design will help me worry more about other parts :-)

     

    Best regards, Enrico Migchels

  • in reply to enrico.migchels

    Hi Enrico,

     

    Very good review. Mine was blocked int he customs but maybe i may have a chance to receive one ( Alistair asked EXAR ). If i receive mine in a way then i will be able to publish my review.

     

    Best regards,

     

    Firat  Kocak

  • in reply to firatkocak

    I know this RoadTest was very popular with members here, so you may be interested in a webinar EXAR are running. The webinar is an introduction and walkthrough creating a programmable digital power supply. More details and registration here

     

     

     

     

     

    Firat, working on it image

  • very good review, good work thnk you.

     

    Lahcen