topic Re: FRDM-MCXN947 deep power down mode. in MCX Microcontrollers

FRDM-MCXN947 deep power down mode.

plac — Fri, 21 Mar 2025 07:56:18 GMT

Hello,

I am trying to evaluate the consumption of an MCX N947 in "deep power down" mode.
For this, I am using a FRDM-MCXN947 board and the demo application from the SDK "power_mode_switch_ll_cm33_core0".
The current measurement is done on J24 (IDD_MCU).
The lowest consumption I observe is about 15uA, far from the 2uA that I am supposed to achieve.
I should note that to reach these 15uA, I disable the MCUlink debugger and keep the Ethernet PHY in reset.
Has anyone ever managed to reach or get close to the 2uA from the datasheet?

I would appreciate any assistance you can offer.

Re: FRDM-MCXN947 deep power down mode.

ZhangJennie — Fri, 21 Mar 2025 09:49:21 GMT

Hi plac,

Low power current parameters of the data sheet are measured with all MCU oscillators and analog domains off. Debug interface will consume power. Make sure to disconnect it. Besides, reasonable configuration of GPIO can further reduce MCU power consumption. Before entering the low power consumption mode, it is recommended to set the unused GPIO as a pull-up input according to the actual situation (It can also be set to output low when the pin is floating). In applications with high requirements for low power consumption, users need to carefully optimize the code design to obtain the best low power consumption design.

I ever made a low power test on LPC board. you can refer it. It's not for MCXN947 but the method is the same.

https://community.nxp.com/t5/LPC-Microcontrollers-Knowledge/LPC-Why-My-Low-Power-Current-Is-Different-From-Manual-Spec/ta-p/1483365

Hope this helps,

Jun Zhang

Re: FRDM-MCXN947 deep power down mode.

plac — Fri, 21 Mar 2025 11:29:52 GMT

Thank you for your response.

I do remove the JTAG during measurements, and the GPIOs are properly configured.
I resolved the issue by adding isolation of the VDD in low power mode by calling the function SPC_SetExternalVoltageDomainsConfig(SPC0, 0x3F, 0x0U).
In this configuration, I obtain 1.3 µA, which is correct.

However, I performed the same test on a proprietary board that has an MCXN547VNLT, and I do not get the same results:
- On the FRDM kit, I measure 15 µA without VDD isolation and 1.3 µA with VDD isolation.
- On our board (MCXN547VNLT), I obtain 8 µA without VDD isolation and 45 µA with VDD isolation.
Additionally, in both cases, I'm not using the internal DC-DC converter but the internal LDO.

Has anyone already performed deep power down measurements on the 547 in the HLQFP100 package?

Re: FRDM-MCXN947 deep power down mode.

ZhangJennie — Fri, 11 Apr 2025 10:01:13 GMT

I suggest you isolating all the possiable peripherals to test again. The existing reverse current may cause this problem.

I addition, you would check to set the unused GPIO as a pull-up input according to the actual situation. Some peripherals may still consum power.

Thanks,

Jun Zhang