LP2950/2951

Micrel

3

February 1999

3-47

Low Battery Disconnect

For values shown, Regulator shuts down when V

IN

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

µA.

System Over Temperature Protection Circuit

* Sets disconnect voltage

** Sets disconnect hysteresis

LM34 for 125

°F Shutdown

LM35 for 125

°C Shutdown

3

LP2951

SD

V

GND

4

1

8

OUT

+VIN

SENSE

2

NI-CAD

BACKUP

BATTERY

20

Ω

+

+

1µF

MAIN V+

MEMORY V+

LM385

1.5k

Ω**

–

100k

Ω

120k

Ω

FB

6V

SEALED

LEAD-

ACID

BATTERY

SOURCE

+

≈ 400kΩ*

FOR 5.5V

1N457

AUX. SHUTDOWN

INPUT

3

MIC2951

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

10k

Ω

5

° PRE-SHUTDOWN FLAG

+VIN

LM34 OR

LM35

TEMP.

SENSOR

8.2k

Ω

–

+

FB

OFF

ON