Datasheet

Clock operation M41T81S

22/32 Doc ID 10773 Rev 7

Output driver pin

When the FT bit, AFE bit, SQWE bit, and watchdog register are not set, the

IRQ

/FT/OUT/SQW pin becomes an output driver that reflects the contents of D7 of the

calibration register. In other words, when D7 (OUT bit) and D6 (FT bit) of address location

08h are a '0,' then the IRQ

/FT/OUT/SQW pin will be driven low.

Note: The IRQ

/FT/OUT/SQW pin is an open drain which requires an external pull-up resistor.

Preferred initial power-on default

Upon initial application of power to the device, the following register bits are set to a '0' state:

watchdog register; AFE; ABE; SQWE; OFIE; and FT. The following bits are set to a '1' state:

ST; OUT; OF; and HT (see Tabl e 5 ).

Table 5. Preferred default values

Condition ST HT Out FT AFE SQWE ABE

WATCHDOG

(1)

OF OFIE

Initial power-up

(2)

11100 0 0 0 1 0

Subsequent power-up

(with battery backup)

(3)

UC 1 UC 0 UC UC UC 0 UC UC

1. BMB0-BMB4, RB0, RB1

2. State of other control bits undefined

3. UC = Unchanged