M41T00AUD_12 STMICROELECTRONICS [STMicroelectronics], M41T00AUD_12 Datasheet - Page 21

• Manufacturer Part Number: M41T00AUD_12
• Description: Serial real-time clock (RTC) with audio
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

M41T00AUD
5.3
Note:
Priority for IRQ/FT/OUT pin
Three functions share pin 5 of the M41T00AUD. The oscillator fail interrupt (IRQ), the
calibration frequency test output (FT) and the discrete logic output (OUT) all use this pin.
In normal operation, when operating from V
frequency test function which in turn has priority over the discrete output function.
In the backup mode, when operating from V
and frequency test functions are disabled, and only the discrete output function can be
used.
When operating from V
09h), the pin is an interrupt output which will be asserted anytime the OF bit (D5 of register
09h) goes true. (See
During calibration, the pin can be used as a frequency test output. When FT is a 1 (and
OFIE a 0), the device will output a 512 Hz test signal on this pin. Users can measure this
with a frequency counter and use that result to determine the appropriate calibration register
value.
Otherwise, when OFIE is a 0 and FT is a 0, it becomes the discrete logic OUT pin and
reflects the value of the OUT bit (D7 of register 07h).
When operating from V
IRQ/FT/OUT pin will reflect the contents of the out bit.
The IRQ/FT/OUT pin is open drain and requires an external pull-up resistor.
Table 5.
On V
On V
State
BACK
CC
Priority for IRQ/FT/OUT pin
Section 5
OFIE
CC
BACK
X
X
1
0
0
0
, if the oscillator fail interrupt enable bit is set (OFIE, D4 of register
, the discrete output function can still be used. The
Doc ID 13480 Rev 5
Register bits
for more details.)
FT
X
X
X
1
0
0
CC
BACK
, the interrupt function has priority over the
OUT
, the priorities are different. The interrupt
X
X
1
0
1
0
M41T00AUD clock operation
IRQ/FT/OUT pin
512 Hertz
OF
1
0
1
0
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