m41t80 STMicroelectronics, m41t80 Datasheet - Page 16

• Manufacturer Part Number: m41t80
• Description: Serial Access Real Time Clock With Alarm
• Manufacturer: STMicroelectronics

Clock operation
3.3
Note:
3.4
16/25
Table 5.
Full-time 32kHz square wave output
The M41T80 offers the user a special 32kHz square wave function which defaults to output
on the F
function is available within four seconds of initial power-up and can only be disabled by
setting the 32kE Bit to '0' or the ST Bit to '1.' If not used, the F
and allowed to float.
The F
Century bit
Bits D7 and D6 of Clock Register 03h contain the CENTURY ENABLE Bit (CEB) and the
CENTURY Bit (CB). Setting CEB to a '1' will cause CB to toggle, either from a '0' to '1' or
from '1' to '0' at the turn of the century (depending upon its initial state). If CEB is set to a '0,'
CB will not toggle.
RS3
32k
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
32k
pin is an open drain which requires an external pull-up resistor.
pin (Pin 3) as long as V
Square wave output frequency
RS2
Square wave bits
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
CC
RS1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
is valid, and the oscillator is running (ST Bit = '0'). This
RS0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
32k
Frequency
pin should be disconnected
32.768
8.192
4.096
2.048
1.024
None
512
256
128
64
32
16
8
4
2
1
Square wave
Units
kHz
kHz
kHz
kHz
kHz
Hz
Hz
Hz
Hz
Hz
Hz
Hz
Hz
Hz
Hz
M41T80
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