Power supply monitoring

Power monitor solutions are available in the device, in order to survey the VDD (battery voltage).

Power supply supervisor

The power supply supervisor enables monitoring of the connected power supply.

Two functionalities are implemented:
  • Power-on reset (POR): Generates a reset when the supply is applied to the device, and ensures that the device starts up in a known state
  • Brownout reset (BOR): Generates a reset when the supply drops below the minimum voltage required for safe operations
Two BOR levels are used:
  • VBOROFF, used in System OFF
  • VBORON, used in System ON

The power supply supervisor is illustrated in the image below.

Figure 1. Power supply supervisor
Power supply supervisor

Battery monitoring on VDD

A battery voltage (VDD) monitoring capability is provided via a modem API

Note: For details regarding the modem API, please refer to nRF Connect SDK document and nRF91 AT Commands, Command Reference Guide document.

Electrical specification

Device startup times

Symbol Description Min. Typ. Max. Units

Time in power-on reset after VDD has reached VPOR (if ENABLE is tied to VDD) or after ENABLE input has been set to to logic high.

.. .. .. ms

The maximum time taken to pull up the nRESET pin and release reset after power-on reset. Dependent on the pin capacitive load (C)1: t=5RC, R=13 kΩ.

.. .. ..  

C=500 nF

.. .. .. ms

C=10 µF

.. .. .. ms

Time from reset to ON (CPU execute)


Time from OFF to CPU execute

36 µs

Time from WFE to CPU execute

22 µs

Time from WFI to CPU execute

33 µs

Time from HW event to PPI event in constant latency System ON mode

.. .. .. µs

Time from HW event to PPI event in low power System ON mode

.. .. .. µs

Power supply supervisor

Symbol Description Min. Typ. Max. Units

Brownout reset voltage threshold.

2.00 V

Voltage threshold at which the device enters power-on reset (POR) when VDD is ramping up.

2.15 V
1 To decrease the maximum time a device could be held in reset, a strong external pull-up resistor can be used.