MIC2950 Ver la hoja de datos (PDF) - Micrel

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MIC2950

150mA Low-Dropout Voltage Regulator

Micrel 

MIC2950/2951

+V = 2 → 30V

I L↓ LOAD

I

L=

1.23V

R

8

VIN

VOUT 1

MIC2951

SHUTDOWN

INPUT

3

SD

OFF GND

FB

ON

4

7

R

1%

1µF

Low Drift Current Source

0.1µF

5V BUS

Micrel

+V IN

VOUT *VOUT≈5V

MIC2950Z

+

1µF

GND

5-Volt Current Limiter

870 27

* MINIMUM INPUT-OUTPUT VOLTAGE RANGES FROM 40mV TO 400mV,

DEPENDING ON LOAD CURRENT.

+V IN

D1

8

+V IN

2

SENSE

VOUT 1

MIC2951

#1

5

ERROR

GND

4

27kΩ

2.7MΩ

D4

D3

D2

MEMORY

V+

20

1µF

3.6V

NICAD

EARLY WARNING

Q1

8

2

+VIN SENSE

VOUT 1

MIC2951

3 SD

#2 ERROR 5

GND

4

330kΩ

MAIN

OUTPUT

RESET

µP

VDO

+ 1µf

Regulator with Early Warning and Auxiliary Output

• EARLY WARNING FLAG ON LOW INPUT VOLTAGE

• MAIN OUTPUT LATCHES OFF AT LOWER INPUT VOLTAGES

• BATTERY BACKUP ON AUXILIARY OUTPUT

OPERATION: REG. #1’S VOUT IS PROGRAMMED ONE DIODE DROP ABOVE 5 V.

ITS ERROR FLAG BECOMES ACTIVE WHEN VIN ≤ 5.7 V. WHEN VIN DROPS

BELOW 5.3 V, THE ERROR FLAG OF REG. #2 BECOMES ACTIVE AND VIA Q1

LATCHES THE MAIN OUTPUT OFF. WHEN VIN AGAIN EXCEEDS 5.7 V REG. #1

IS BACK IN REGULATION AND THE EARLY WARNING SIGNAL RISES,

UNLATCHING REG. #2 VIA D3.

3-60

870 29

February 1999

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