ST10F276E datasheet(114/235 Pages) STMICROELECTRONICS

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System reset

ST10F276E

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Doc ID 12303 Rev 3

Synchronous reset and RPD pin

Whenever the RSTIN pin is pulled low (by external hardware or as a consequence of a

Bidirectional reset), the RPD internal weak pull-down is activated. The external capacitance

(if any) on RPD pin is slowly discharged through the internal weak pull-down. If the voltage

level on RPD pin reaches the input low threshold (around 2.5V), the reset event becomes

immediately asynchronous. In case of hardware reset (short or long) the situation goes

immediately to the one illustrated in Figure 26. There is no effect if RPD comes again above

the input threshold: the asynchronous reset is completed coherently. To grant the normal

completion of a synchronous reset, the value of the capacitance shall be big enough to

maintain the voltage on RPD pin sufficient high along the duration of the internal reset

sequence.

For a Software or Watchdog reset event, an active synchronous reset is completed

regardless of the RPD status.

It is important to highlight that the signal that makes RPD status transparent under reset is

the internal RSTF (after the noise filter).

Figure 28.

Synchronous short / long hardware RESET (EA = 1)

RSTIN assertion can be released there. Refer also to Section 19.1 for details on minimum pulse duration.

If during the reset condition (RSTIN low), RPD voltage drops below the threshold voltage (about 2.5V for

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