M41ST87W datasheet(33/54 Pages) STMICROELECTRONICS

部件名	M41ST87W

功能描述	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

Scroll/Zoom	100%

制造商	STMICROELECTRONICS [STMicroelectronics]

网页	http://www.st.com

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33 / 54 page

M41ST87W

Clock operation

DocID9497 Rev 11

33/54

interrupt function. This is easily handled by simply reading past the flags registers before

teminating a read sequence.

The

IRQ/OUToutputisclearedbyaREADtotheflagsregister.AsubsequentREADofthe

flags register is necessary to see that the value of the alarm flag has been reset to '0.'

The

IRQ/OUTpincanalsobeactivatedinthebatterybackupmode.TheIRQ/OUTwillgo

low if an alarm occurs and both ABE (alarm in battery backup mode enable) and AFE are

set. The ABE and AFE bits are reset during power-up, therefore an alarm generated during

power-up will only set AF. The user can read the flag register at system boot-up to

determine if an alarm was generated while the M41ST87Y/W was in the deselect mode

during power-up. Figure 25: "Backup mode alarm waveform" illustrates the backup mode

alarm timing.

Figure 24: Alarm interrupt reset waveform

Table 9: Alarm repeat modes

RPT5

RPT4

RPT3

RPT2

RPT1

Alarm setting

Once per second

Once per minute

Once per hour

Once per day

Once per month

Once per year

IRQ/OU T

ACTIVE FLAG

0Fh

0Eh

10h

HIGH-Z

ADDRESS POINTER

M41ST87W 数据表(PDF) 33 Page - STMicroelectronics

M41ST87W 数据表(HTML) 33 Page - STMicroelectronics

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