STEC01 datasheet(11/22 Pages) STMICROELECTRONICS

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6.4

HW_RESET functionality

The HW_RESET input can be used to monitor an input power line (e.g. USB) to notify the connection to the

platform control unit.

When the signal on the HW_REST pin is more than VHW_RESET threshold, after a deglitch time of the 10 ms

(typ.), a 57 ms (typ.) pulse is generated on the RESET/FAULT output pin. If several pulses longer than the

deglitch time are detected, during the RESET/FAULT low time, the pulse duration is extended (see events (a) and

(b) in the example below).

Figure 9. HW_RESET input functionality

RESET/FAULT

(a)

HW_RESET

(b)

(c)

57ms

a) HW_RESET is higher than VHW_RESET threshold for more than the deglitch time of 10 ms (typ.), a 57 ms reset

fault pulse is generated

b) HW_RESET goes down and rises again above the VHW_RESET threshold for more than the deglitch time, a new

50 ms reset fault signal is generated overlapping the previous one

c) HW_RESET is higher than VHW_RESET threshold for more than deglitch time on rising edge and remains high

Note:

A Schmitt trigger is used in the input stage of HW_RESET. If the HW_RESET is used for USB VBus line

monitoring, during USB disconnection, in case of voltage bouncing, a reset might be generated.

STEC01

HW_RESET functionality

DS13063 - Rev 2

page 11/22

STEC01 Datasheet(PDF) 11 Page - STMicroelectronics