Diodes AP1533 User Manual

AP1533

PWM CONTROL 1.8A STEP-DOWN CONVERTER

Features

• Input voltage: 4V to 23V

• Output voltage: 0.8V to V

• 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

• Built-in internal SW P-channel MOS

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

(No Br, Sb)

• Lead Free Finish/ RoHS Compliant (Note 1)

CC

Applications

• PC Motherboard

• LCD Monitor

• Graphic Card

• DVD-Video Player

• Telecom Equipment

• ADSL Modem

• Printer and other Peripheral Equipment

• Microprocessor core supply

General Description

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.

Typical Application Circuit

V

=5V/1.8A

L1

33uH

C

Optional

D1*

R

C

A

6.8K

R

B

1.3K

C

OCSET

Option

EN

EN

Vcc

Output

AP1533

1+

FB

V

SS

R

/R

)

B

A

OCSET

EN

V

OUT

x (

V

FB

=

= 0.7K~5K ohm

R

B

Suggested DIODES Power Schottky P/N: B340 series or PDS340.

*

V

IN

R

OCSET

3.3K

C

IN

470uF

CVcc

0.1uF

R
100K

C

0.1uF

AP1533 Rev. 4 1 of 9 JULY 2009
DS31192 www.diodes.com © Diodes Incorporated

OUT

+

+

C

0.1uF 470uF

-

-

C

OUT

Ordering Information

AP1533

PWM CONTROL 1.8A STEP-DOWN CONVERTER

AP 1 5 3 3 S G - 13

Device

Package Packing

S : SOP-8L

Package

Code

Packaging

(Note 2)

Green

G : Green

13 : Tape & Reel

13” Tape and Reel

Quantity Part Number Suffix

AP1533SG-13 S SOP-8L 2500/Tape & Reel -13

Notes: 1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at
http://www.diodes.com/products/lead_free.html.

2. Pad layout as shown on Diodes Inc. suggested pad layout document AP02001, which can be found on our website at
http://www.diodes.com/datasheets/ap02001.pdf.

Pin Assignments

FB

EN

OCSET

V

CC

1

2

3

4

( Top View )

AP1533

SOP-8L

8

7

6

5

V

SS

V

SS

Output

Output

Pin Descriptions

Pin Name Pin No. Description

FB 1 Feedback pin

Power-off pin
H: Normal operation

EN 2

OCSET 3 Add an external resistor to set max output current

VCC 4 IC power supply pin

(Step-down operation)

L: Step-down operation stopped

(All circuits deactivated)

Output 5, 6

Switch Pin. Connect external inductor/diode here. Minimize trace area at this pin
to reduce EMI

VSS 7, 8 GND Pin

AP1533 Rev. 4 2 of 9 JULY 2009
DS31192 www.diodes.com © Diodes Incorporated

A

Block Diagram

AP1533

PWM CONTROL 1.8A STEP-DOWN CONVERTER

Output

Oscillation

Circuit

V

CC

PWM-Switched
Control Circuit

Thermal

Shutdown

V

EN

EN

Voltage Source

90uA

OCSET

Reference

+

-

FB

V

SS

Absolute Maximum Ratings

Symbol Parameter Rating Unit

ESD HBM Human Body Model ESD Protection

8

ESD MM Machine Model ESD Protection 500 V

V

VCC Pin Voltage V

CC

V

Feedback Pin Voltage V

FB

V

EN Pin Voltage V

EN

V

Switch Pin Voltage VSS - 0.3 to VIN + 0.3 V

OUT

P

Power Dissipation Internally limited mW

D

T

Operating Junction Temperature Range -20 to +125

J

T

Storage Temperature Range -65 to +150

ST

Caution: The absolute maximum ratings are rated values exceeding which the product could suffer physical damage.
These values must therefore not be exceeded under any conditions.

- 0.3 to VSS + 24 V

SS

- 0.3 to VCC V

SS

- 0.3 to VIN + 0.3 V

SS

Recommended Operating Conditions

Symbol Parameter Min Max Unit

VIN Input Voltage 4 23 V

I

Output Current 0 1.8

OUT

TA Operating Ambient Temperature -25 85

KV

o

C

o

C

o

C

AP1533 Rev. 4 3 of 9 JULY 2009
DS31192 www.diodes.com © Diodes Incorporated