MP8903 – LOW DROPOUT, 150mA LINEAR REGULATOR

MP8903 Rev. 1.11

www.MonolithicPower.com

5

4/4/2011

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PIN FUNCTIONS

QFN8

(2x2mm)

Pin #

TSOT23-5

Pin #

Name Description

1

2

GND Ground.

2

3

EN

Enable Input. Drive EN high to turn on the MP8903; low to turn it off. For

automatic startup, connect EN to IN.

3, 4

1

IN

Power Source Input. IN supplies the internal power to the MP8903 and is the

source of the pass transistor. Bypass IN to GND with a 1µF or greater

capacitor.

5, 6

5

OUT

Regulator Output. OUT is the output of the linear regulator. Bypass OUT to

GND with a 1µF or greater capacitor.

7

NC

No Connect.

8

4

FB

Feedback Input. Connect a resistive voltage divider from OUT to FB to set the

output voltage. The OUT feedback threshold is 1.222V.

OPERATION

The MP8903 is a low-current, low-dropout

linear regulator. The MP8903 uses a PMOS

pass element and features internal thermal

shutdown. The normally fixed output MP8903

may be converted to an adjustable output device

by applying a resistor divider network as shown in

Figure 2. An optional feed-forward capacitor,

response.

C3

GND

FB

OUT

--

+

BANDGAP

REFERENCE

INTERNAL

RESISTOR

DIVIDER

Figure 1—Fixed Output Regulator

R1

R2

--

+

BANDGAP

REFERENCE

GND

FB

OUT

EXTERNAL

RESISTOR

DIVIDER