m41t00cap STMicroelectronics, m41t00cap Datasheet - Page 9

• Manufacturer Part Number: m41t00cap
• Description: Serial Access Real-time Clock With Integral Backup Battery
• Manufacturer: STMicroelectronics

M41T00CAP
3
3.1
3.2
Operation
The M41T00CAP clock operates as a slave device on the I
by implementing a start condition followed by the correct slave address (D0h). The 8 bytes
contained in the device can then be accessed sequentially in the following order:
1.
2.
3.
4.
5.
6.
7.
8.
The M41T00CAP clock continually monitors V
V
address counter. Inputs to the device will not be recognized at this time to prevent erroneous
data from being written to the device from a an out-of-tolerance system. Once V
below the switchover voltage (V
and powers down into an ultra-low current mode of operation to prolong battery life. If V
is less than V
V
drops below V
V
For more information on battery storage life refer to application note AN1012.
Wire bus characteristics
The bus is intended for communication between different ICs. It consists of two lines: a
bidirectional data signal (SDA) and a clock signal (SCL). Both the SDA and SCL lines must
be connected to a positive supply voltage via a pull-up resistor.
The following protocol has been defined:
●
●
●
Accordingly, the following bus conditions have been defined:
Bus not busy
Both data and clock lines remain high.
CC
BAT
CC
. If V
fall below V
rises above V
Seconds register
Minutes register
Century/hours register
Day register
Date register
Month register
Year register
Calibration register
Data transfer may be initiated only when the bus is not busy.
During data transfer, the data line must remain stable whenever the clock line is high.
Changes in the data line, while the clock line is high, will be interpreted as control
signals.
BAT
is greater than V
PFD
PFD
PFD
, the device power is switched from V
. Upon power-up, the device switches from battery to V
PFD
, the device terminates an access in progress and resets the device
, the inputs will be recognized.
PFD
SO
, the device power is switched from V
), the device automatically switches over to the battery
CC
for an out-of-tolerance condition. Should
CC
to V
2
C serial bus. Access is obtained
BAT
when V
CC
CC
CC
to V
at V
drops below
BAT
CC
SO
Operation
when V
. When
falls
BAT
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CC