STM1403ASMQ6F datasheet(12/34 Pages) STMICROELECTRONICS

12 / 34 page

Pin descriptions

STM1403

12/35

STM1403A (VOUT remains ON when SAL is active-low): Vccsw pin will continue to

operate in normal mode;

STM1403B (VOUT is taken to High-Z when SAL is active-low): Vccsw pin will be set to

high when this occurs; and

STM1403C (VOUT is driven to ground when SAL is active-low): Vccsw pin will be set to

high when this occurs.

2.1.4

BLD, VBAT low voltage detect output (open drain)

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

three customer options for VDET:

●

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

This output pin will go active-low when it detects a voltage on the VBAT pin below VDET. BLD

will be released when VCC drops below VRST.

2.1.5

Active-low RST output (open drain)

Goes low and stays low when VCC drops below VRST (reset threshold selected by the

customer), or when MR is logic low. It remains low for trec (200ms, typical) AFTER VCC rises

above VRST and MR goes from low to high.

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

is low and for trec after MR returns to high. This active low input has an internal 40 kΩ

(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)

When PFI is less than VPFI (power-fail input threshold voltage) or VCC falls below VSW

(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

When PFI is less than VPFI, or when VCC falls below VSW (see PFO, above), PFO goes

active-low. If this function is unused, connect this pin to VSS.

2.1.9

VREF, reference voltage output (1.237, typ)

This is valid only when VCC is between 2.4 V and 3.6 V. When VCC falls below 2.4 V (VSW),

VREF is pulled to ground with an internal 100 kΩ resistor. This is an optional feature

available on the STM1403A. On the STM1403B/C, this pin is VTPU (internally switched VCC

or VBAT). If unused, this pin should float.

STM1403ASMQ6F Datasheet(PDF) 12 Page - STMicroelectronics

STM1403ASMQ6F Datasheet(HTML) 12 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

Datasheet Download

Link URL