M41ST87W datasheet(28/52 Pages) STMICROELECTRONICS

部件名	M41ST87W

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

PDF	52 Pages

Scroll/Zoom	100%

制造商	STMICROELECTRONICS [STMicroelectronics]

网页	http://www.st.com

标志

28 / 52 page

Operating modes

M41ST87Y, M41ST87W

28/52

Doc ID 9497 Rev 8

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 3.0.1: Power-down time-stamp on page 29) 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 PFO is asserted.

M41ST87W 数据表(PDF) 28 Page - STMicroelectronics