Nordic nPM1300 Power Management IC EK RoadTest

Table of contents

RoadTest: Enroll to Review the Nordic nPM1300 Power Management IC Eval Kit

Author: flyingbean

Creation date: 4 Mar 2024

Evaluation Type: Evaluation Boards

Did you receive all parts the manufacturer stated would be included in the package?: True

What other parts do you consider comparable to this product?: NA

What were the biggest problems encountered?: The battery power input has no strong over-voltage protection. The battery profiling daughter board is not included into the evaluation kit, which prevented users to evaluate battery gauge feature of nPM1300.

Detailed Review:

1. Unboxing Nordic nPM1300 EK

I received the Nordic nPM1300 evaluation kit in the middle of January, 2024. The mailed package was already covered with a coat of snow. I hoped that there would be any trouble inside of the EK package.

After I unboxed the mailed package, the Nordic nPM1300 EK package seemed not wetting.

The hardware version of the kit is V0.9.1. Nordic website listed more than 4 different versions of nPM1300 EK platform.  There are known issues with nPM1300 EK as below.

The first impression of nPM 1300 EV platform is that so many extended ports are available to evaluate every pin of nPM 1300 IC without extra hardware work. There are 20 ports, 4 jacks, and 4 push buttons. The PC test point natural type is used for 4 main power rails and GND, which make the board level testing task more user friendly. I circled PC test point natural type in red at the picture below. There are two USB type C connectors: the upper one is for USB power charging and the lower one is for the communication between nPM1300 EV and Nordic nPM PowerUP GUI at a host PC.

Figure 1: nPM1300 Evaluation Kit

2. nPM1300 Evaluation Kit Roadtest

nPM1300 is a new generation IC chip for advanced power management. It is a good candidate PMIC for low power and IoT applications. The integrated system management features very interesting functions, such as watchdog, power-loss warning, battery life profiling, fuel gauge, supporting battery charging system, etc. The nPM1300 evaluation kit allows developers to set up the testing bed with minimal testing circuit mock-up. Nordic also supplies an intuitive desktop GUI to evaluate nPM1300, which is called nRF Connect for Desktop(v4.3.0) .

nPM1300 PMIC has two main power suppliers: VBUS and VBAT. VUSB is from USB port and VBAT is from a battery. Figure 2 uses the arrows to illustrate the power current directions. The orange arrow demonstrates the battery charging current direction. The red arrow demonstrates non-battery charging current.

Figure 2: nPM1300 Power Current Flow Illustration

nPM1300 PMIC has two configurable 200mA BUCK regulators and two 50mA LDO/100mA load switches.  In addition, an unregulated power rail, VBUSOUT, delivers up to 1340mA when powered from battery or up to 1.5A when powered from a USB port.

Figure 3 presents the power rail voltage ranges from Nordic document (Ref[1]).

Figure 3: nPM1300 EK Power Rail Voltage Range

I finished these roadtest items:

Power rail: VBUS, VBAT, VSYS, 2 BUCK voltage regulators.

VUBS undervoltage protection, overvoltage protection.

VBAT undervoltage protection and overvoltage test.

Battery fuel gauge.

VDDIO input is evaluated.

I did not do these roadtest items:

VLDO power rails.

I finished these roadtest items:

Power rail: VBUS, VBAT, VSYS, 2 BUCK voltage regulators.

VBUS undervoltage protection, overvoltage protection.

VBAT undervoltage protection and overvoltage test.

Battery fuel gauge.

VDDIO input is evaluated.

I did not do these roadtest items:

VLDO power rails.

Battery profiling.

Figure 4 presents the chargeable battery and testing loads for the experiments:

a. NCR3400MAH, 3.7V, 3400mAH, Lithium Battery from Amazon.

b. RC1206FR-071RL, Yageo, 1 Ω 1/4W, 1%, SMD resistors.

c. RS2B, Dale, 1 Ω, 3W, 1%, through-hole resistors, axial wirewound.

d. 45F1R0E, Ohmite, 100 Ω, 3W, 5%, through-hole resistors, axial wirewound.

Figure 4: Chargeable Battery and High-Power Resistors

2.1 Power rail chain #1: VBUS->VSYS->BUCK1/BUCK2

The bench testing was set up as Figure 5. The resistive load was configured at 11 Ω for BUCK1 and 15 Ω for BUCK2.

Figure 5: nPM1300 EK bench testing for BUCK1 and BUCK2

Vout1 is the output from BUCK1 and Vout2 is the output from BUCK2. There are jumpers to configure BUCK1 and BUCK2 at the startup of the voltage converters as Figure 6. VSET1/VSET2 pins are enabled only at power-on. If there is a voltage level predefined at VSET1/VSET2 pins, Vout1/Vout2 can be configured between 0V and 2.7V or 3.3V. I used nPM1300-EK hardware defined RSET1, which is 47K Ω for 1.8V at Vout1; and RSET2, which is 150K Ω for 3.0V at Vout2.

Figure 6: Buck Power Rail Startup Configuration

I configured VBUS input voltage from 3V to 6 V as below. There is no load for VSYS power rail.

Figure 7: VBUS_OUT Over/under Voltage Protection

From the datasheet of nPM1300 at Ref[2], I found that VBUS power design does provide a very robust undervoltage and overvoltage protection at SYSREG circuity.

VSYS was measured at 5.24V when VUBS=5.29V from the bench testing, which is close to the graph from nPM1300 datasheet. I marked my testing results as “X” in the graph as below. The similar color “X” means similar VBUS input. The I_limit is 500mA by default of nPM1300 configuration.

Figure 8: VSYS Power Rail Evaluation

The calculated power efficiency from this bench setup is presented blow.

I did not find the power efficiency graph of VBUS from nPM1300 datasheet. Here is my bench testing result of VBUS power efficiency for the bench testing setup in this review. The overall 90% power efficiency is pretty good.

Figure 9: nPM1300 Power Efficiency from VBUS

2.2 Power rail chain #2: VBAT->VSYS->BUCK1 and BUCK2

I used GW Instek GPD-2303S power supply as VBAT input to evaluate nPM1300 performance. Basing on nPM1300 datasheet, VBAT voltage range is 2.3~4.5V. There is no any information about under-voltage or over-voltage protection data.

I used similar bench testing setup as Figure 5 to evaluate VBAT power input performance. The measured data is presented below.

When VBAT =2.5V, Vout1/Vout2 is not stable, so there is no recorded data in the table.

Figure 10: nPM1300 Power Rails from VBAT Input

The calculated VBAT power efficiency is provided as below.

Figure 11: VBAT Power Efficiency

The power efficiency at VBAT=3.8V from my bench testing setup is around 92% at IOUT=150~180mA, which is marked “X” in the graph comparing with the VBAT power efficiency performance from nPM1300 datasheet as below.

Figure 12: Measured VBAT Power Efficiency vs nPM1300 Datasheet

The battery charger is suitable for general purpose applications with lithium-ion (Li-ion), lithium-polymer

(Li-poly), and lithium iron phosphate (LiFePO4) batteries. nPM PowerUP utility from Nordic is used for battery charging experiment.

Figure 13: Nordic nPM PowerUP Utility

The bench setup loop is presented below.

Figure 14: Battery Charging Bench Testing Setup

uPM PowerUP utility can automatically detect the Li-poly type battery. I selected a sample battery model from uPM PowerUP as the GUI illustration below.

Figure 15: Battery Fuel Gauge GUI on uPM PowerUP

The fuel gauge reading seems reasonable for me since I did charge the NCR3400MHA battery in full. I need to select Ignore NTC in order to charge the battery since there is no temperature sensor in the rechargeable battery. I set Ichg=32mA to charge the battery. The current of the battery charging is detected as -32mA and Constant Voltage for charging mode.

I cannot get nPM-FG board from Nordic America distributor before I finished the roadtest. I did get some help about how to use  uPM PowerUP to do battery profiling from Nordic DevZone. Here is the answer from Nordic regarding 3400mAH Li-poly type battery as follows.

3. VBAT Power Rail Experiment Discussions

nPM1300 datasheet mentions that VBAT voltage range is  -0.3V ~ 5.5V.

From Figure 10, you might find that I did configure VBAT at 6.5V and nPM1300 still functioned well. However, the good news was not last very long. There was an incident happening while I tried to repeat VBAT at 6.5V~7V for the experiment: I_VSYS_max = 690mA. Then VSYS became almost 0V. After the incident, VSYS is no long function. However, due to BUCK power rails (Vout1 and Vout2) need the input power from VSYS as Figure 2 defined on the evaluation kit, Vout1 and Vout2 do not function as well now.

From what I learned after the incident, the power current budget needs to be understood as this way:

        a. CHARGER 800mA = I_VSYS + 200mA@BUCK1 + 200mA@BUCK2

        b. SYSREG 1500mA = I_VSYS + 200mA@BUCK1 + 200mA@BUCK2

There is some overvoltage protection at VBAT/CHARGER block, however, the board level design might need to add a voltage clamp before VBAT if a voltage spike is needed to be suppressed. For example a voltage clamp at 6V is a good pratice.

4. Conclusions

nPM1300 EK is a good evaluation kit for PMIC part, such as nPM1300. The expanded pins make the evaluation work very fast and accurate enough. VBUS/SYSREG is very robust for undervoltage/overvoltage protection. The hardware configurable voltage of the two buck power rail is   convenient. However, due to the incident of VBAT testing, VSYS power rail was damaged, I cannot finish my scheduled testing plan.  The power efficient seems very good from what I tested.

In summary, I finished over 80% of my test plan. If I have a chance to get another nPM1300 EK kit, I will test LDO power rails and more battery modeling/profiling features.

Some feedback for nPM1300 design/application:

      a.VBAT protection part might need more information on the datasheet since there is no robust overvoltage protection for VBAT. VBUS does have a very strong cutoff method for overvoltage protection.

      b. VBAT power budget calculation: Do BUCK1 and BUCK2 has to be supplied from VSYS or not? If it is YES, then 800mA from CHARGER is not purely for VSYS, because BUCK1/BUCK2 and LDO1/LDO2 will share some of 800mA from CHARGER.

References

[1] nPM1300_EK_User_Guide_v0.9.1.pdf

[2] nPM1300_PS_v1.0.pdf