Copyright

© ANPEC Electronics Corp.

Rev. B.4 - Mar., 2008

APL5331

www.anpec.com.tw

11

Block Diagram

Pin Description

PIN NAME

I/O

DESCRIPTION

VIN

I

Main power input pin. Connect this pin to a voltage source and an input capacitor. The

APL5331 sources current to VOUT pin by controlling the upper NPN pass transistor, providing

a current path from VIN pin.

GND

O

Power and signal ground. Connect this pin to system ground plane with shortest traces. The

APL5331 sinks current from VOUT pin by controlling the lower NPN pass transistor, providing

a current path to GND pin. This pin is also the ground path for internal control circuitry.

VCNTL

I

Power input pin for internal control circuitry. Connect this pin to a voltage source, providing a

bias for the internal control circuitry. A bypass capacitor is usually connected near this pin.

VREF

I

Reference voltage input and active-low shutdown control pin. Apply a voltage to this pin as a

reference voltage for the APL5331. Connect this pin to a resistor divider, between VIN and

GND, and a capacitor for soft-start and filtering noise purposes. Applying and holding this

VREF voltage low by an open-drain transistor to shut down the output.

VOUT

O

Output pin of the regulator. Connect this pin to load. The output capacitors connected to this

pin improve stability and transient response. The output voltage tracks the reference voltage

and is capable of sourcing or sinking current up to 3A.

GND

VOUT

VIN

VCNTL

VREF

Current

Limit

Thermal

Limit

Voltage

Regulation

Shutdown