M41T94 datasheet(23/41 Pages) STMICROELECTRONICS

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M41T94

Clock operations

23/41

4.6

Power-on reset

The M41T94 continuously monitors VCC. When VCC falls to the power fail detect trip point,

the RST pulls low (open drain) and remains low on power-up for tREC after VCC passes VPFD

(max). The RST pin is an open drain output and an appropriate pull-up resistor should be

chosen to control rise time.

4.7

Reset inputs (RSTIN1 & RSTIN2)

The M41T94 provides two independent inputs which can generate an output reset. The

duration and function of these resets is identical to a reset generated by a power cycle.

Table 7 on page 24 and Figure 13 on page 24 illustrate the AC reset characteristics of this

function. Pulses shorter than tRLRH1 and tRLRH2 will not generate a reset condition. RSTIN1

and RSTIN2 are each internally pulled up to VCC through a 100kΩ resistor.

Table 6.

Square wave output frequency

Square wave bits

Square wave

RS3

RS2

RS1

RS0

Frequency

Units

0000

None

–

0001

32.768

kHz

0010

8.192

kHz

0011

4.096

kHz

0100

2.048

kHz

0101

1.024

kHz

0110

512

0111

256

1000

128

1001

1010

1011

11008

11014

11102

11111

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