M41ST84WMQ6E STMicroelectronics, M41ST84WMQ6E Datasheet - Page 25

• Manufacturer Part Number: M41ST84WMQ6E
• Description: IC RTC 3.0V 512BIT NVRAM 16SOIC
• Manufacturer: STMicroelectronics
• Type: Clock/Calendar/Supervisorr

Specifications of M41ST84WMQ6E

• Memory Size: 64B
• 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: 16-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-2802-5; M41ST84WMQ6

M41ST84W
3.10
3.11
Note:
3.12
3.13
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.
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 M41ST84W 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 battery may be replaced while
V
The M41ST84W only monitors the battery when a nominal V
Thus 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
of the deselect time after V
WRITEs may again be performed to the device after a power-down condition. The t
allow the user to set the length of this deselect time as defined by
rec
CC
is applied to the device.
bit
CC
is supplied. In order to insure data integrity during subsequent periods of
CC
reaches V
Doc ID 7530 Rev 9
PFD
rec
bit (TR). t
. This allows for a voltage setting time before
rec
refers to the automatic continuation
CC
is applied to the device.
Table 7 on page
Clock operation
rec
26.
bit will
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