Power supplies

AN3216

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DocID17496 Rev 7

Figure 6. PVD thresholds

2.3.3

Brownout reset (BOR)

During power on, the brownout reset (BOR) keeps the device under reset until the supply

For devices operating from 1.65 to 3.6 V, the BOR option is not available and the power

supply is monitored by the POR/PDR. As the POR/PDR thresholds are at 1.5 V, a “grey

1.65 V.

For devices operating from 1.8 to 3.6 V, the BOR is always active at power on and its

threshold is 1.8 V.

When the system reset is released, the BOR level can be reconfigured or disabled by option

byte loading.

If the BOR level is kept at the lowest level, 1.8 V at power-on and 1.65 V at power down, the

system reset is fully managed by the BOR and the product operating voltages are within

safe ranges.

When the BOR option is disabled by option byte, the power down reset is controlled by the

system can start.

BOR can be disabled by programming the device option bytes. To disable the BOR function,

sequence. The power-on and power-down is then monitored by the POR and PDR (see

power-on reset (POR)/power-down reset (PDR) section in the product datasheets).

The BOR threshold hysteresis is ~100 mV (between the rising and the falling edge of the

supply voltage).

PVD output

100 mV

hysteresis

PVD threshold