AP1533

PWM CONTROL 1.8A STEP-DOWN CONVERTER

AP1533 Rev. 4

1 of 9

JULY 2009

DS31192

www.diodes.com

•

Input voltage: 4V to 23V

•

•

Output current: 1.8A up to peak 2A

•

Duty ratio: 0% to 99% PWM control

•

Oscillation frequency: 300KHz typ.

•

Soft-start like, Current limit and Enable function

•

Thermal Shutdown function

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Built-in internal SW P-channel MOS

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SOP-8L: Available in “Green” Molding Compound

(No Br, Sb)

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Lead Free Finish/ RoHS Compliant (Note 1)

AP1533 consists of step-down switching regulator with PWM

control. These devices include a reference voltage source,

oscillation circuit, error amplifier, internal PMOS.

AP1533 provides low-ripple power, high efficiency, and excellent

transient characteristics. The PWM control circuit is able to vary

the duty ratio linearly from 0 up to 99%. This converter also

contains an error amplifier circuit as well as a soft-start circuit that

prevents overshoot at startup. An enable function, an over current

protect function and a short circuit protect function are built inside,

and when OCP or SCP happens, the operation frequency will be

reduced from 300KHz to 50KHz. Also, an internal compensation

block is built in to minimum external component count.

With the addition of an internal P-channel Power MOS, a coil,

capacitors, and a diode connected externally, these ICs can

function as step-down switching regulators. They serve as ideal

power supply units for portable devices when coupled with the

SOP-8L mini-package, providing such outstanding features as low

current consumption. Since this converter can accommodate an

input voltage up to 23V, it is also suitable for the operation via an

AC adapter.

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PC Motherboard

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LCD Monitor

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Graphic Card

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DVD-Video Player

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Telecom Equipment

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ADSL Modem

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Printer and other Peripheral Equipment

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Microprocessor core supply

Typical Application Circuit

AP1533

+

-

V

SS

EN

C

C

R

A

R

B

D1

*

FB

Vcc

Output

CVcc

V

V

IN

R

OCSET

OCSET

C

OUT

C

IN

Optional

C

OCSET

C

EN

R

EN

Option

100K

L1

33uH

6.8K

1.3K

3.3K

0.1uF

+

-

C

0.1uF

470uF

470uF

0.1uF

R

Features

General Description

Applications