contact-fact Micrel Semiconductor, contact-fact Datasheet - Page 12

• Manufacturer Part Number: contact-fact
• Description: Mic2950/mic2951 150ma Low-dropout Voltage Regulator
• Manufacturer: Micrel Semiconductor

MIC2950/2951
MIC2950/2951
ON
SHUTDOWN
INPUT
O F F
Low Drift Current Source
3
I L
S D
GND
+V = 2
MIC2951
4
LOAD
V IN
1%
8
• 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
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
#1 IS BACK IN REGULATION AND THE EARLY WARNING SIGNAL RISES, UN-
LATCHING REG. #2 VIA D3.
R
F B
30V
V
OUT
7
Regulator with Early Warning and Auxiliary Output
I L =
1µF
1
1.23V
Q1
Q1
R
3
3
2.7MΩ
2.7MΩ
SD
SD
+V IN
+V IN
+V IN
+V IN
+V IN
+V IN
0.1µF
MIC2951
MIC2951
8
8
8
8
GND
GND
GND
GND
OUT
4
4
#2
4
4
#1
IS PROGRAMMED ONE DIODE DROP ABOVE 5
SENSE
SENSE
SENSE
SENSE
D 4
D 4
ERROR
ERROR
ERROR
ERROR
V
V
V
V
2
2
2
2
OUT
OUT
OUT
OUT
27kΩ
27kΩ
12
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,
IN
DEPENDING ON LOAD CURRENT.
AGAIN EXCEEDS 5.7 V REG.
330kΩ
330kΩ
IN
OUTPUT
OUTPUT
≤ 5.7 V. WHEN V
EARLY WARNING
EARLY WARNING
MAIN
MAIN
+
+
1µF
1µF
D 2
D 2
1µf
1µf
MEMORY
MEMORY
RESET
RESET
V DO
V DO
20
20
3.6V
3.6V
NICAD
NICAD
V+
V+
µP
µP
MIC2950Z
5V BUS
IN
+V IN
5-Volt Current Limiter
DROPS
G ND
V
O UT
*V
O UT
+
1µF
= 5V
Micrel, Inc.
July 2005
870 27
870 29