M41ST87YMX6TR datasheet(27/54 Pages) STMICROELECTRONICS

Teilenummer	M41ST87YMX6TR

Bauteilbeschribung	5.0 and 3.3/3.0 V secure serial RTC and NVRAM supervisor with tamper detection and 128 bytes of clearable NVRAM

PDF	54 Pages

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Hersteller	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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M41ST87W

Operating modes

DocID9497 Rev 11

27/54

2.11

Tamper event time-stamp

Regardless of which tamper occurs first, not only will the appropriate tamper bit be set, but

the event will also be automatically time-stamped. This is accomplished by freezing the

normal update of the clock registers (00h through 07h) immediately following a tamper

event. Thus, when tampering occurs, the user may first read the time registers to determine

exactly when the tamper event occurred, then re-enable the clock update to the current

time (and reset the tamper bit, TBX) by resetting the tamper enable bit (TEBX).

The time update will then resume and the clock can be read to determine the current time.

Both tamper enable bits (TEBX) must always be set to '0' in order to read the current time.

In the event of multiple tampers, the time-stamp will reflect the initial tamper event.

Note: If the TEBX bit is set, the tamper event time-stamp will take precedence over the

power down time-stamp (see Section 3.1: "Power-down time-stamp") and the HT bit (halt

update) will not be set during the power-down event. If both are needed, the power down

time-stamp may be accomplished by writing the time into the general purpose RAM

memory space when

PFOisasserted.

M41ST87YMX6TR Datenblatt(PDF) 27 Page - STMicroelectronics