Reset and power supply supervisor
AN4488
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AN4488 Rev 7
power on/power down reset threshold, refer to the electrical characteristics in the product
datasheets.
Figure 9. Power-on reset/power-down reset waveform
1. t
RSTTEMPO
is approximately 2.6 ms. V
POR/PDR
rising edge is 1.74 V (typ.) and V
POR/PDR
falling edge is
1.70 V (typ.). Refer to STM32F4xxxx datasheets for actual value.
The internal power-on reset (POR) / power-down reset (PDR) circuitry is disabled through
the PDR_ON pin. An external power supply supervisor should monitor V
DD
and should
maintain the device in reset mode as long as V
DD
is below a specified threshold. PDR_ON
should be connected to this external power supply supervisor. See
for details.
3.2.3 Programmable
voltage detector (PVD)
You can use the PVD to monitor the V
DD
power supply by comparing it to a threshold
selected by the PLS[2:0] bits in the Power control register (PWR_CR).
The PVD is enabled by setting the PVDE bit.
A PVDO flag is available, in the Power control/status register (PWR_CSR), to indicate
whether V
DD
is higher or lower than the PVD threshold. This event is internally connected to
EXTI Line16 and can generate an interrupt if enabled through the EXTI registers. The PVD
output interrupt can be generated when V
DD
drops below the PVD threshold and/or when
V
DD
rises above the PVD threshold depending on the EXTI Line16 rising/falling edge
configuration. As an example the service routine can perform emergency shutdown tasks.
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HYSTERESIS
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AIB
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FALLINGEDGE
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RISINGEDGE