diodes incorporated AP1520 Service Manual

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Features

• Input Voltage: 3.6V to 23V

• Output Voltage: 0.8V to V

• Duty Ratio: 0% to 100% PWM Control

• Oscillation Frequency: 300KHz typ.

• Soft-Start, Current Limit, Enable Function

• Thermal Shutdown Function

• Built-in Internal SW P-Channel MOS

• SOP-8L Pb-Free Package

• Lead Free Finish/RoHS Compliant (Note 1)

CC

AP1520

PWM CONTROL 2A STEP-DOWN CONVERTER

General Description

AP1520 consists of step-down switching regulator with PWM control.
These devices include a reference voltage source, oscillation circuit,
error amplifier, and internal PMOS.

AP1520 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 100%. This converter also contains
an error amplifier circuit as well as a soft-start circuit that prevents
overshooting 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 30KHz. 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.

Applications

• PC Motherboard

• LCD Monitor

• Graphic Card

• DVD-Video Player

• Telecom Equipment

• ADSL Modem

• Printer and other Peripheral Equipment

• Microprocessor Core Supply

• Networking Power Supply

Ordering Information

AP1520 X X X

Package

S: SOP-8L -U : Tube

Note: 1. RoHS revision 13.2.2003. Glass and High Temperature Solder Exemptions Applied, see EU Directive Annex Notes 5 and 7.

Lead-Free

L : Lead-Free

Lead-free

Note: 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.

Device

(Note 2)

AP1520S S SOP-8L 100/Tube -U 2500/Tape & Reel -13

Package

Code

Packaging

Quantity Part Number

AP1520 Rev. 1 1 of 8 JANUARY 2007

www.diodes.com © Diodes Incorporated

Packing

-13 : Taping

Tube 13” Tape and Reel

Quantity Part Number

Suffix

Suffix

A

AP1520

Pin Assignments

( Top View )

1

FB

2

EN

AP1520

OCSET

3

4

V

CC

SOP-8L

PWM CONTROL 2A STEP-DOWN CONVERTER

Pin Descriptions

Description

8

7

6

5

Vss

Vss

Output

Output

Name

OCSET 3

Output 5, 6

Pin

FB 1 Feedback pin

EN 2

VCC

VSS

Pin

No.

Power-off pin
H: Normal operation
(Step-down operation)
L: Step-down operation stopped
(All circuits deactivated)

dd an external resistor to set max

output current

4 IC power supply pin

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

7, 8 GND Pin

Block Diagram

V

cc

Thermal

Shutdown

Output

Oscillation

Circuit

EN

PWM-Switched
Control Circuit

EN

Reference Voltage

Source with Soft Start

+

-

100uA

OCSET

FB

VssV

AP1520 Rev. 1 2 of 8 JANUARY 2007

www.diodes.com © Diodes Incorporated

AP1520

PWM CONTROL 2A STEP-DOWN CONVERTER

Absolute Maximum Ratings

Symbol Parameter Rating Unit

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 Temperature Range -20 to +85

OPR

T

Storage Temperature Range -40 to +150

STG

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.

Electrical Characteristics ( VIN = 12V, T

= 25°C, unless otherwise specified )

a

Symbol Parameter Conditions Min. Typ. Max. Unit

VIN Input Voltage -- 3.6 - 23 V

VFB Feedback Voltage I

IFB Feedback Bias Current I

= 0.1A 0.784 0.8 0.816 V

OUT

= 0.1A - 0.1 0.5 µA

OUT

ISW Switch Current -- 2.5 - - A

Current Consumption

I

SSS

During Power off

∆V

OUT

/V

∆V

/V

f

f

VSH Evaluate oscillation at SW pin 2.0 - -

I

OCSET

Line Regulation V

OUT

OUT

Load Regulation I

OUT

Oscillation Frequency Measure waveform at SW pin 240 300 360 KHz

OSC

Frequency of Current Limit

OSC1

or Short Circuit Protect

EN Pin Input Voltage

VSL

ISH -- - 20 - µA

EN Pin Input Leakage
Current

ISL

Measure waveform at SW pin 10 - - KHz

Evaluate oscillation stop at SW pin - - 0.8

OCSET Pin Bias Current -- 75 90 105 µA

V

= 0V - 10 - µA

EN

= 5V~23V - 1 2 %

IN

= 0.1 to 2A - 0.2 0.5 %

OUT

-- - -10 - µA

TSS Soft-Start Time -- 0.3 1 2 ms

R

Internal MOSFET R

DSON

EFFI Efficiency

Thermal Resistance

θJA

Junction-to-Ambient

DSON

= 5V, V

IN

= 12V, V

V

IN

V

= 12V, V

IN

I

OUT

= 0V - 110 150

FB

= 0V - 70 100

FB

= 5V

OUT

= 2A

- 65 -

V

- 0.3 to VSS + 25 V

SS

- 0.3 to VCC V

SS

- 0.3 to VIN + 0.3 V

SS

o

C

o

C

V

mΩ

- 92 - %

o

C/W

AP1520 Rev. 1 3 of 8 JANUARY 2007

www.diodes.com © Diodes Incorporated