nrf52832 always restart while power supply voltage between 0.6V - 1.0V

[Liny]

i found that 52832 will always restart while power supply voltage between 0.6V - 1.0V。if lower than 0.6V or higher than 1.0V. it won‘t happen。my pseudo code is follow：

power on by key；

            ↓

if （battery_val < 2.0 V）

{

        NRF_LOG_INFO("detect low power！");

        NRF_POWER->SYSTEMOFF = POWER_SYSTEMOFF_SYSTEMOFF_Enter;
        __DSB();
        while (true) {__WFE();}

}

and i found the log will print always，it seems likes mcu enter system off mode and restart right away。

i catch resetreas register ，and the result is pin-reset。but i hadn‘t define "CONFIG_GPIO_AS_PINRESET",so it's strange.

could you provide me some advice?

thanks.

[Kenneth]

Hi,

The minimum VDD voltage to execute code is 1.7V, if the voltage fall below this the chip will enter brown out reset (BOR) until voltage rise above 1.7V.

While the chip is in system OFF mode, the BOR will trigger between 1.2V and 1.7V:
https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/power.html#unique_2766336

While the chip is in system ON idle mode, the BOR will trigger between 1.5V and 1.7V.

If you experience BOR below these levels, then I think it may get power through a GPIO (e.g. do you have a debugger connected?).

i catch resetreas register ，and the result is pin-reset。but i hadn‘t define "CONFIG_GPIO_AS_PINRESET",so it's strange.

You should run an 'nrfjprog --eraseall' to ensure UICR is erased, and thereby also pin reset will be disabled. It might have been defined earlier during development.

Kenneth

[Liny]

thanks for your answer

i found something wrong i said earlier.

that is,The 0.9V power supply is actually changed to 3.3V through the regulated power supply。

and our product would pull down the 3.3V voltage to 2.3V while power on。

i use Oscilloscope to watch what happened at that time, and the result as follow:

and i found the resetreas is 0x00 ,whtich means power-on reset or a brownout reset .but i can't explain it .so could you help me to find the reasons?

very thanks!

[Kenneth]

You can find here a description that explain your problem:
https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/power.html#concept

"A step increase in supply voltage of 300 mV or more, with rise time of 300 ms or less, within the valid supply range, may result in a system reset."

Best regards,
Kenneth