Unable to Power nRF9151 DK from External 4.2V Supply Provided by RT700 EVK.

[Suhas0]

Hello Team,

We are evaluating an architecture where an NXP MIMXRT700 EVK powers an nRF9151 DK externally while using the nRF9151 DK as an LTE modem.

Hardware:

• MIMXRT700 EVK
• nRF9151 DK
• Jio LTE SIM

Based on the nRF9151 DK documentation, we found:

"External supply on pin VIN 5V of connector P20. Supported input voltage range: 4.0V to 5.5V."

Test Performed:

1. Powered the RT700 EVK through USB.
2. Measured approximately 4.2V between J23 Pin 5 (VSYS) and GND on the RT700 EVK.
3. Connected:
   • RT700 J23 Pin 5 (VSYS ~4.2V) -> nRF9151 DK VIN 5V (P20)
   • RT700 GND -> nRF9151 DK GND
4. Removed USB power from the nRF9151 DK.
5. Attempted to power the nRF9151 DK solely from the RT700 EVK supply.

Result:

• The nRF9151 DK did not power up.
• No power LED activity was observed.

Questions:

1. Is VIN 5V on connector P20 the correct location for supplying external power to the nRF9151 DK?
2. Are any jumpers, switches, solder bridges, or power path configurations required when powering the board through VIN 5V instead of USB?
3. Is 4.2V sufficient for powering the complete nRF9151 DK, considering the documented 4.0V–5.5V input range?
4. Is there a minimum startup current requirement that could prevent the board from powering up?
5. Are there any recommended test points or measurements we should check to verify that external power is reaching the board correctly?

Our goal is to determine whether the nRF9151 DK can be powered from another embedded platform (RT700 EVK) while maintaining LTE functionality.

Any guidance would be appreciated.

Thank you.

[JONATHAN LL]

HI, 

I am not familiar with RT700 EVK but if it can deliver 5V and have sufficient current to supply then I dont see why the nRF9150DK should not be able to run. If you just want to use the nRF91 LTE part then you can power only that section as well by supplying VDGPIO and VDD_nRF separately with the correct SB cutt. 

The DK uses a nPM1300 to supply the VDD_GPIO for the nRF9151 as well as the onboard debugger. 

There should be a jumper that connects VDD_nRF to VIN_5V on P22. If not you can short SB34. 

Is VIN 5V on connector P20 the correct location for supplying external power to the nRF9151 DK?

Yes. just make sure the power switch is still "ON" and that the P22 has the jumper between VIN_5V and VDD_nRF. 

Are any jumpers, switches, solder bridges, or power path configurations required when powering the board through VIN 5V instead of USB?

only P22 by default(it should come with the jumper), you can use SB34 or R82 as well. 

Is 4.2V sufficient for powering the complete nRF9151 DK, considering the documented 4.0V–5.5V input range?

Yes this should be fine. 

Are there any recommended test points or measurements we should check to verify that external power is reaching the board correctly?

You can measure on VDD_nRF to see if there is power there or not on P20 and you can check if VDD_GPIO also gets power there. 


Regards,
Jonathan