LP2951-4.8BM Micrel Semiconductor, LP2951-4.8BM Datasheet - Page 11

• Manufacturer Part Number: LP2951-4.8BM
• Description: 100mA Low-Dropout Voltage Regulator
• Manufacturer: Micrel Semiconductor

LP2950/2951
February 1999
SHUTDOWN
INPUT
Low Drift Current Source
3
I L
SD
GND
+V = 2
4
LP2951
LOAD
V IN
1%
8
R
30V
FB
V
OUT
7
• 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
ITS ERROR FLAG BECOMES ACTIVE WHEN V
BELOW 5.3 V, THE ERROR FLAG OF REG. #2 BECOMES ACTIVE AND VIA Q1
LATCHES THE MAIN OUTPUT OFF. WHEN V
IS BACK IN REGULATION AND THE EARLY WARNING SIGNAL RISES,
UNLATCHING REG. #2 VIA D3.
I L =
1 F
1
1.23
Regulator with Early Warning and Auxiliary Output
R
Q1
3
2.7M
0.1 F
SD
+V IN
+V IN
+V IN
LP2951
LP2951
8
8
OUT
GND
GND
4
4
#1
#2
IS PROGRAMMED ONE DIODE DROP ABOVE 5 V.
SENSE
SENSE
D 4
ERROR
ERROR
V
V
2
2
OUT
OUT
27k
3-45
D 1
D 3
* MINIMUM INPUT-OUTPUT VOLTAGE RANGES FROM 40mV TO 400mV,
5
5
1
1
DEPENDING ON LOAD CURRENT.
IN
IN
AGAIN EXCEEDS 5.7 V REG. #1
330k
OUTPUT
5.7 V. WHEN V
EARLY WARNING
MAIN
+
1 F
D 2
1 f
MEMORY
RESET
V DO
20
3.6V
NICAD
LP2950Z
V+
IN
P
+V IN
+V
DROPS
GND
5 Volt Current Limiter
IN
V
OUT
+
*V
1 F
OUT
= 5V
Micrel
3