NRF52811-QCAA-R7 datasheet(51/444 Pages) NORDIC

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Power and clock management

POFCON

MUX

Vpof

1.7V

2.8V

POFWARN

VBOR

Brownout reset

Power on reset

VDD

Figure 15: Power supply supervisor

5.3.4.1 Power-fail comparator

The power-fail comparator (POF) can provide the CPU with an early warning of impending power failure. It

will not reset the system, but give the CPU time to prepare for an orderly power-down.

The comparator features a hysteresis of VHYST, as illustrated in Power-fail comparator (BOR = Brownout

reset) on page 51. The threshold VPOF is set in register POFCON on page 58. If the POF is enabled

and the supply voltage falls below VPOF, the POFWARN event will be generated. This event will also be

generated if the supply voltage is already below VPOF at the time the POF is enabled, or if VPOF is re-

configured to a level above the supply voltage.

If power-fail warning is enabled and the supply voltage is below VPOF the power-fail comparator will

prevent the NVMC from performing write operations to the NVM. See NVMC — Non-volatile memory

controller on page 19 for more information about the NVMC.

VDD

VPOF

VPOF+VHYST

1.7V

BOR

Figure 16: Power-fail comparator (BOR = Brownout reset)

To save power, the power-fail comparator is not active in System OFF or in System ON when HFCLK is not

running.

4454_140 v1.0

NRF52811-QCAA-R7 Datasheet(PDF) 51 Page - Nordic Semiconductor