LP2951

DS20005736B-page 4



2017 - 2022 Microchip Technology Inc. and its subsidiaries

For values shown, Regulator shuts down when V

IN

< 5.5V and turns on again at 6.0V. Current drain in disconnected mode is 150 μA.

* Sets disconnect voltage

** Sets disconnect hysteresis

3

LP2951

SD

V

GND

4

1

8

OUT

+VIN

SENSE

2

NI-CAD

BACKUP

BATTERY

20Ω

+

+

1 μF

MAIN V+

MEMORY V+

LM385

1.5 kΩ**

–

100 kΩ

120kΩ

FB

6V

SEALED

LEAD-

ACID

BATTERY

SOURCE

+

≈ 400 kΩ*

FOR 5.5V

1N457

LOW BATTERY DISCONNECT

LM34 for 125°F Shutdown

LM35 for 125°C Shutdown

AUX. SHUTDOWN

INPUT

3

LP2951

SD

V

GND

4

5

8

OUT

+VIN

ERROR

1

7

RELAY

EXTERNAL CIRCUIT

PROTECTED FROM

OVER TEMPERATURE

(V+ GOES OFF WHEN

TEMP.> 125°)

OR

10 kΩ

5° PRE-SHUTDOWN FLAG

+V

IN

LM34 OR

LM35

TEMP.

SENSOR

8.2 kΩ

–

+

FB

OFF

ON

SYSTEM OVERTEMPERATURE

PROTECTION CIRCUIT