nRF51822 resets when power drops below 2.1V

[Rashid Talib]

Hi When I reduce the operating voltage, the nRF51822 with the heart rate demo running resets whenever the voltage drops below 2.1V and does not recover unless I increase the voltage level and reset the chip. According to the datasheet, operation down to 1.8V is possible when the DC/DC converter is disabled.

• I checked the POFCON register, the power supply supervisor is disabled
• I checked the DCDCEN register, the DC/DC converter is disabled.

What else could cause this reset? I did not find any further info in the datasheet or sample code.

Thanks for your help & best regards Rashid

[Håkon Alseth]

Hi,

Are you certain that the voltage does not dip under 1.8V and activate the Brown-out-Detector? If you have high ripple on VDD, it can go below and trigger this behavior.

Try scoping the VDD line when this occurs.

Best regards Håkon