M41T94MQ6 STMicroelectronics, M41T94MQ6 Datasheet - Page 26

• Manufacturer Part Number: M41T94MQ6
• Description: Real Time Clock Serial 512 (64x8)
• Manufacturer: STMicroelectronics

Specifications of M41T94MQ6

• Function: Clock, Calendar, Alarm, Timer Interrupt
• Rtc Memory Size: 64 B
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 2.7 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Rtc Bus Interface: Serial
• Package / Case: SO-16
• Time Format: HH:MM:SS:hh
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Clock operations
4.10
Note:
4.11
Note:
4.12
26/41
Output driver pin
When the FT bit, AFE bit and watchdog register are not set, the IRQ/FT/OUT pin becomes
an output driver that reflects the contents of D7 of the control register. In other words, when
D7 (OUT bit) and D6 (FT bit) of address location 08h are a '0,' then the IRQ/FT/OUT pin will
be driven low.
The IRQ/FT/OUT pin is an open drain which requires an external pull-up resistor.
Battery low warning
The M41T94 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 backup mode, the battery should be replaced. The SNAPHAT
while V
This will cause the clock to lose time during the interval the SNAPHAT
disconnected.
The M41T94 only monitors the battery when a nominal V
applications which require extensive durations in the battery backup 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.
t
Bit D7 of clock register 04h contains the t
continuation of the deselect time after V
time before WRITEs may again be performed to the device after a power-down condition.
The t
on page
REC
REC
CC
bit
27.
bit will allow the user to set the length of this deselect time as defined by
CC
is applied to the device.
is supplied. In order to insure data integrity during subsequent periods of
CC
REC
reaches V
bit (TR). t
PFD
REC
. This allows for a voltage setting
CC
refers to the automatic
is applied to the device. Thus
®
®
top may be replaced
battery/crystal top is
Table 8
M41T94