LP2950/LP2951
TYPICAL APPLICATIONS
(Continued)
2 Ampere Low Dropout Regulator
CURRENT
LIMIT SECTION
Regulator with Early Warning and Auxiliary Output
+V
IN
8
+V
IN
6
V
TAP
2
SENSE
V
OUT
1
D
2
5V MEMORY
SUPPLY
+V
IN
= V
OUT
+.5V
D
1
680
0.05
470
7
2N3906
4.7M
Ω
8
+V
IN
ERROR
LP2951
3
SD
GND
4
20k
Ω
.033
FB
V
OUT
1
5
ERROR
FLAG
7
R
1
1%
R
2
+
+
10k
Ω
MJE2955
+V
OUT
@ 2A
LP2951
#1
5
ERROR
FB
GND
4
+
1µF
20
3.6V
NICAD
27 kΩ
4.7
TANT.
100
µ
F
2.7MΩ
D
4
Q
1
6
7
3
D
3
EARLY WARNING
220
8
+V
IN
V
TAP
FB
SD
2
SENSE
V
OUT
330 kΩ
MAIN 5V OUTPUT
RESET
µP
V
DD
LP2951
#2
5
ERROR
GND
4
+
1µF
VOUT = 1.23V(1+R1/R2)
For 5V V
OUT
, use internal resistors. Wire pin 6 to 7 and pin 2 to +V
OUT
Buss.
•
Early warning flag on low input voltage
•
Main output latches off at lower input voltages
•
Battery backup on auxiliary output
Operation: Reg.#1’s V
OUT
is programmed one diode drop above 5V. It’s error flag
becomes active when V
IN
≤
5.7V. When V
IN
drops below 5.3V, the error flag of
Reg.#2 becomes active and via Q1 latches the main output off. When V
IN
again
exceeds 5.7V Reg.#1 is back in regulation and the early warning signal rises,
unlatching Reg.#2 via D3.
1A Regulator with 1.2V Dropout
UNREGULATED
INPUT
1µF
10kΩ
0.01µF
SUPERTEX
VP12C
8
IN
6
V
TAP
SENSE
LP2951
7
FB
GND
4
OUT 1
0.002µF
2kΩ
I
Q
≅
400µA
2
+
220µF
OUTPUT
5V ± 1% @
0 TO 1A
Latch Off When Error Flag Occurs
+V
IN
470kΩ
5
470kΩ
8
+V
IN
1
V
OUT
ERROR
LP2951
3 SD
FB
GND
4
7
R
1
+
1µF
V
OUT
RESET
R
2
1ΜΩ
Advanced Monolithic Systems, Inc.
www.advanced-monolithic.com
Phone (925) 443-0722
Fax (925) 443-0723
ADMOS [ ADVANCED MONOLITHIC SYSTEMS ]
