APW7089 データシートの表示（PDF） - Anpec Electronics

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APW7089

4A, 26V, 380kHz, Asynchronous Step-Down Converter

Anpec Electronics 

APW7089

Pin Description

PIN

NO.

NAME

1

VIN

2

EN

3

UGND

4

VCC

5

LX

6

COMP

7

8

9

(Exposed Pad)

FB

GND

LX

FUNCTION

Power Input. VIN supplies the power (4.5V to 26V) to the control circuitry, gate driver and

step-down converter switch. Connecting a ceramic bypass capacitor and a suitably large

capacitor between VIN and GND eliminates switching noise and voltage ripple on the input to

the IC.

Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on the

regulator, drive it low to turn it off. Pull up with 100kΩ resistor for automatic start-up.

Gate driver power ground of the P-channel Power MOSFET. A linear regulator regulates a 5.5V

voltage between VIN and UGND to supply power to P-channel MOSFET gate driver. Connect a

ceramic capacitor (1µF typ.) between VIN and UGND for noise decoupling and stability of the

linear regulator.

Bias input and 4.2V linear regulator’s output. This pin supplies the bias to some control circuits.

The 4.2V linear regulator converts the voltage on VIN to 4.2V to supply the bias when no

external 5V power supply is connected with VCC. Connect a ceramic capacitor (1µF typ.)

between VCC and GND for noise decoupling and stability of the linear regulator.

Power Switching Output. Connect this pin to the underside Exposed Pad.

Output of error amplifier. Connect a series RC network from COMP to GND to compensate the

regulation control loop. In some cases, an additional capacitor from COMP to GND is required

for noise decoupling.

Feedback Input. The IC senses feedback voltage via FB and regulate the voltage at 0.8V.

Connecting FB with a resistor-divider from the output set the output voltage in the range from

0.8V to 90% VIN.

Power and Signal Ground.

Power Switching Output. LX is the Drain of the P-channel MOSFET to supply power to the

output. The Exposed Pad provides current with lower impedance than Pin 5. Connect the pad to

output LC filter via a top-layer thermal pad on PCBs. The PCB will be a heat sink of the IC.

Block Diagram

VIN

VCC

FB

COMP

EN

VCC

4.2V Regulator

and

Power-On-Reset

POR

Current

-Limit

70%VREF

UVP

Soft-Start

Soft-Start

and

Fault Logic

VREF

0.8V

Error

Amplifier

Current Sense

Amplifier

Inhibit

Gate

Control

Current

Compartor

UG

Gate

Driver

2.5V

0.8V

ENOK

Enable

Over-

Temperature

Protection

Slope

Compensation

Oscillator

FB

380kHz

Linear

VIN

Regulator

UGND

LX

GND

Copyright © ANPEC Electronics Corp.

11

Rev. A.1 - Jan., 2012

www.anpec.com.tw

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