M41ST87WMX6TR STMicroelectronics, M41ST87WMX6TR Datasheet - Page 37

• Manufacturer Part Number: M41ST87WMX6TR
• Description: IC SUPERVISOR RTC 160X8 28-SOIC
• Manufacturer: STMicroelectronics
• Type: Clock/Calendar/Supervisorr

Specifications of M41ST87WMX6TR

• Memory Size: 160B
• Time Format: HH:MM:SS:hh (24 hr)
• Date Format: YY-MM-DD-dd
• Interface: I²C, 2-Wire Serial
• Voltage - Supply: 2.7 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-SOIC, 28-SOH (8.48mm Width)
• Bus Type: Serial (2-Wire, I2C)
• Operating Supply Voltage (typ): 3.3V
• Operating Supply Voltage (max): 3.6V
• Operating Supply Voltage (min): 2.7V
• Operating Temperature Classification: Industrial
• Operating Temperature (max): 85C
• Operating Temperature (min): -40C
• Pin Count: 28
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6457-2; M41ST87WMX6TR

M41ST87Y, M41ST87W
Note:
3.11
3.12
Note:
3.13
output will be configured as open drain (with I
PFOD is set to '0,' the outputs will be configured as full-CMOS (sink and source current as
specified in
When configured as open drain (PFOD = '1'), PFO
up resistor.
Century bits
These two bits will increment in a binary fashion at the turn of the century, and handle leap
years correctly. See
Output driver pin
When the TIE bit, OFIE bit, AFE bit, and watchdog register are not set to generate an
interrupt, the IRQ/OUT pin becomes an output driver that reflects the contents of D7 of the
control register. In other words, when D7 (OUT Bit) is a '0,' then the IRQ/OUT pin will be
driven low. With the ABE bit set to '1,' the OUT pin will continue to be driven low in battery
backup.
The IRQ/OUT pin is an open drain which requires an external pull-up resistor.
Battery low warning
The M41ST87Y/W automatically performs battery voltage monitoring upon power-up and at
factory-programmed time intervals of approximately 24 hours. The battery low (BL) bit, bit
D4 of flags register 0Fh, will be asserted if the battery voltage is found to be less than
approximately 2.5 V. The BL bit will remain asserted until completion of battery replacement
and subsequent battery low monitoring tests, either during the next power-up sequence or
the next scheduled 24-hour interval.
If a battery low is generated during a power-up sequence, this indicates that the battery is
below approximately 2.5 volts and may not be able to maintain data integrity in the SRAM.
Data should be considered suspect and verified as correct. A fresh battery should be
installed.
If a battery low indication is generated during the 24-hour interval check, this indicates that
the battery is near end of life. However, data is not compromised due to the fact that a
nominal V
battery back-up mode, the battery should be replaced. The battery may be replaced while
V
The M41ST87Y/W only monitors the battery when a nominal V
Thus applications which require extensive durations in the battery back-up mode should be
powered-up periodically (at least once every few months) in order for this technique to be
beneficial. Additionally, if a battery low is indicated, data integrity should be verified upon
power-up via a checksum or other technique.
CC
is applied to the device.
CC
Table 17 on page
is supplied. In order to insure data integrity during subsequent periods of
Table 11 on page 38
42).
for additional explanation.
OL
as specified in
1
and PFO
2
Table 17 on page
will require an external pull-
CC
is applied to the device.
Clock operation
42). When
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