LP2950-xx/LP2951-xx
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
4.7MΩ
8
+V
IN
ERROR
3
220
20kΩ
.033
LP2951
SD
GND
4
FB
V
OUT
1
5
ERROR
FLAG
7
R
1
1%
R
2
Q
1
6
7
3
+
+
4.7
TANT.
100μF
2.7MΩ
10kΩ
MJE2955
+V
OUT
@ 2A
LP2951
#1
5
FB
ERROR
GND
4
+
20
1μF
3.6V
NICAD
27 kΩ
D
3
D
4
EARLY WARNING
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
2kΩ
I
Q
≅
400μA
2
+
220μF
OUTPUT
5V ± 1% @
0 TO 1A
Latch Off When Error Flag Occurs
+V
IN
470kΩ
8
+V
IN
5
ERROR
V
OUT
1
V
OUT
470kΩ
LP2951
3 SD
RESET
GND
4
FB
7
R
1
+
R
2
1μF
1ΜΩ
0.002μF
:
ADD.: RM. 4004,
88
BLOCK B,
B
4004
,
:210008
(TEL.): (86)-25-68853600
(FAX): (86)-25-68853600-810
WEB-SITE: WWW.HN-ELEC.COM
NEW WORLD CENTRE,
NO. 88 ZHUJIANG ROAD,
11
NANJING 210008,
CHINA
HN [ NANJING HONANO ELECTRONIC CO., LTD. ]
