MIC2951-4.8BM Micrel Semiconductor, MIC2951-4.8BM Datasheet - Page 12

• Manufacturer Part Number: MIC2951-4.8BM
• Description: 150mA Low-Dropout Voltage Regulator
• Manufacturer: Micrel Semiconductor

MIC2950/2951
ON
SHUTDOWN
INPUT
Low Drift Current Source
OFF
3
I L
SD
GND
+V = 2
MIC2951
4
LOAD
V IN
• 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.
1%
8
R
FB
30V
V
OUT
7
Regulator with Early Warning and Auxiliary Output
I L =
Q1
Q1
1 F
3
3
1
1.23V
2.7M
2.7M
R
SD
SD
+V IN
+V IN
+V IN
+V IN
+V IN
+V IN
MIC2951
MIC2951
8
8
8
8
0.1 F
GND
GND
GND
GND
4
4
#2
4
4
OUT
#1
SENSE
SENSE
SENSE
SENSE
IS PROGRAMMED ONE DIODE DROP ABOVE 5 V.
D 4
D 4
ERROR
ERROR
ERROR
ERROR
V
V
V
V
2
2
2
2
OUT
OUT
OUT
OUT
27k
27k
3-60
D 1
D 1
D 3
D 3
5
5
5
5
1
1
1
1
* MINIMUM INPUT-OUTPUT VOLTAGE RANGES FROM 40mV TO 400mV,
DEPENDING ON LOAD CURRENT.
IN
IN
AGAIN EXCEEDS 5.7 V REG. #1
330k
330k
OUTPUT
OUTPUT
5.7 V. WHEN V
EARLY WARNING
EARLY WARNING
MAIN
MAIN
+
+
1 F
1 F
D 2
D 2
1 f
1 f
MEMORY
MEMORY
RESET
RESET
V DO
V DO
20
20
IN
MIC2950Z
3.6V
3.6V
NICAD
NICAD
V+
V+
DROPS
5V BUS
P
P
+V IN
5-Volt Current Limiter
GND
V
OUT
*V
OUT
+
1 F
5V
February 1999
Micrel
870 27
870 29