PRODUCT SPECIFICATION
Typical Applications (continued)
39kΩ
RESET
8
2
+VIN SENSE
5
1
ERROR VOUT
RC2951
–
*C4
3
SD
7
FB
+
GND VTAP
39kΩ
4
6
+VOUT = 5V
+
1µF
+ 6V
100
Lead-Acid 1% kΩ
–
Battery
C1
+
C1-C4
LP339
1% 1kΩ
–
C2
+
1% 1kΩ
–
C3
+
10kΩ
R3
1% 20kΩ
100kΩ
< 5.8V**
100kΩ
< 6.0V**
100kΩ
< 6.2V**
*Optional Latch off when drop out occurs. Adjust R3 for C2 Switching when Vin is 6.0V.
**Outputs go low whenVin drops below designated thresholds.
Figure 12. Regulator with State-of-Charge Indicator
For values shown, Regulator shuts down when Vin < 5.5V and turns on again at 6.0V. Current drain in disconnected mode is ≈ 150 µA.
6V
+ Sealed
Lead-Acid
Battery
Source
≈ 400kΩ*
for 5.5V
120kΩ
1.5kΩ**
+
FB LM385
–
100kΩ
1N457
8
+VIN
1
VOUT
3
SD
RC2951
2
SENSE
7
FB
GND VTAP
4
6
+
1µF
*Sets disconnect Voltage
**Sets disconnect Hysteresis
Figure 13. Low Battery Disconnect
Main V+
Memory V+
20Ω
+
Ni-cad
Backup
Battery
2950-14
RC2951
9