Pin descriptions

STM1403

12/35

1.

operate in normal mode;

2.

high when this occurs; and

3.

high when this occurs.

2.1.4

This is an internally loaded test of the battery, activated only during a power-up sequence to

insure that the battery is good either prior to or after encapsulation of the module. There are

●

2.3 V (2.5 V – external diode drop of about 0.2 V) for a 3 V lithium cell

●

2.5 V (2.7 V – 0.2 V) for a 3 V lithium cell or

●

3.2 V (3.4 V – 0.2 V) for a 3.68 V lithium “AA” battery

2.1.5

Active-low RST output (open drain)

2.1.6

MR, manual reset input

A logic low on MR asserts the RST output. The RST output remains asserted as long as MR

(typical) pull-up resistor. It can be driven from a TTL or CMOS logic line or shorted to ground

with a switch. Leave it open if unused.

2.1.7

PFO, power-fail output (open drain)

(battery switchover threshold ~ 2.4 V), PFO goes low, otherwise, PFO remains high. Leave

this pin open if unused.

2.1.8

PFI, power-fail input

2.1.9