LP2950ACDT-5RKG Datasheet, PDF (12/22 Pages) ON Semiconductor – 100 mA, Low Power Low Dropout Voltage Regulator

LP2950, LP2951, NCV2951
+V_in
8
5 _Error ^Vin _Vout ¹
D1
SNS ²
LP2951CN
NC ³ SD ^#1 _{VO T} ⁶
GND FB
4
7
D2
1.0 mF
Memory
V+
20
3.6 V
NiCad
27 k
D3
2.7 M
Q1
D4
2N3906
330 k
8
5 _Error ^Vin _Vout ¹
SNS ²
LP2951CN
3 _SD #2 _{VO T} 6
GND FB
4
7
Early Warning
Reset
mP
V_DD
Main
Output
1.0 mF
All diodes are 1N4148.
Early Warning flag on low input voltage.
Main output latches off at lower input voltages.
Battery backup on auxiliary output.
Operation: Regulator #1’s V_out is programmed one
diode drop above 5.0 V. Its error flag becomes active
when V_in < 5.7 V. When V_in drops below 5.3 V, the
error flag of regulator #2 becomes active and via Q1
latches the main output “off”. When V_in again exceeds
5.7 V, regulator #1 is back in regulation and the early
warning signal rises, unlatching regulator #2 via D3.
Figure 25. Regulator with Early Warning and Auxiliary Output
Current Limit
+V_in
Section
680
2N3906
470
0.05
1000 mF
2N3906
4.7 M
Error
Flag
220
20 k
MJE2955
10 k .33 mF
8
5 _Error ^Vin _Vout ¹
SNS ² NC
LP2951CN
3 _SD
V_O T ^{6 NC}
GND FB .01 mF
4
7
47
V_out @ 2.0 A
4.7 mF
Tant
R1
100 mF
R2
0.033 mF
V_out = 1.25V (1.0 + R1/R2)
For 5.0 V output, use internal resistors. Wire Pin 6 to 7,
and wire Pin 2 to +V_out Bus.
Figure 26. 2.0 A Low Dropout Regulator
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