m41t64 STMicroelectronics, m41t64 Datasheet - Page 23

no-image

m41t64

Manufacturer Part Number
m41t64
Description
Serial Access Real-time Clock With Alarms
Manufacturer
STMicroelectronics
Datasheet

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
m41t64Q6F
Manufacturer:
ST
0
Part Number:
m41t64Q6F
Manufacturer:
ST
Quantity:
20 000
Company:
Part Number:
m41t64Q6F
Quantity:
2 500
Century Bits
These two bits will increment in a binary fashion at
the turn of the century, and handle all leap years
correctly. See
explanation.
Output Driver Pin (M41T62/65)
When the OFIE Bit, AFE Bit, and watchdog regis-
ter are not set to generate an interrupt, the IRQ/
OUT pin becomes an output driver that reflects the
contents of D7 of the Calibration Register. In other
words, when D7 (OUT Bit) is a '0,' then the IRQ/
OUT pin will be driven low.
Note: The IRQ/OUT pin is an open drain which re-
quires an external pull-up resistor.
Oscillator Stop Detection
If the Oscillator Fail (OF) Bit is internally set to a '1,'
this indicates that the oscillator has either stopped,
or was stopped for some period of time and can be
used to judge the validity of the clock and date da-
ta. This bit will be set to '1' any time the oscillator
stops.
In the event the OF Bit is found to be set to '1' at
any time other than the initial power-up, the STOP
Bit (ST) should be written to a '1,' then immediately
reset to '0.' This will restart the oscillator.
Table 9. Initial Power-on Default Values
Note: 1. All other control bits power-up in an undetermined state.
Table 10. Century Bits Examples
Note: 1. Leap year occurs every four years (for years evenly divisible by four), except for years evenly divisible by 100. The only exceptions
Initial
Power-up
Condition
are those years evenly divisible by 400 (the year 2000 was a leap year, year 2100 is not).
(1)
CB0
0
0
1
1
M41T62
M41T63
M41T64
M41T65
Device
Table 10., page 23
ST
0
0
0
0
OF
1
1
1
1
OFIE
N/A
N/A
0
0
for additional
CB1
0
1
0
1
OUT
N/A
N/A
1
1
N/A
N/A
N/A
FT
0
The following conditions can cause the OF Bit to
be set:
If the Oscillator Fail Interrupt Enable Bit (OFIE) is
set to a '1,' the IRQ pin will also be activated. The
IRQ output is cleared by resetting the OFIE or OF
Bit to '0' (NOT by reading the Flag Register).
The OF Bit will remain set to '1' until written to logic
'0.' The oscillator must start and have run for at
least 4 seconds before attempting to reset the OF
Bit to '0.' If the trigger event occurs during a power-
down condition, this bit will be set correctly.
Initial Power-on Defaults
Upon application of power to the device, the regis-
ter bits will initially power-on in the state indicated
in Table 9.
AFE
N/A
N/A
0
0
The first time power is applied (defaults to a '1'
on power-up).
Note: If the OF Bit cannot be written to '1' four
(4) seconds after the initial power-up, the
STOP Bit (ST) should be written to a '1,' then
immediately reset to '0.'
The voltage present on V
insufficient to support oscillation.
The ST Bit is set to '1.'
External interference of the crystal
Leap Year?
SQWE
N/A
Yes
No
No
No
1
1
0
32KE
N/A
N/A
N/A
1
RS3-1
N/A
0
0
0
CC
M41T62/63/64/65
Example
or battery is
RS0
N/A
2000
2100
2200
2300
1
1
1
Watchdog
(1)
0
0
0
0
23/33

Related parts for m41t64