Diodes AP1509 User Manual

AP1509

150KHz, 2A PWM BUCK DC/DC CONVERTER

Description

The AP1509 series are monolithic IC designed for a step­down DC/DC converter, and own the ability of driving a
2A load without additional transistor. It saves board space.
The external shutdown function can be controlled by logic
level and then come into standby mode. The internal
compensation makes feedback control having good line and
load regulation without external design. Regarding protected
function, thermal shutdown is to prevent over temperature
operating from damage, and current limit is against over
current operating of the output switch. If current limit function
occurs and V
will be reduced. The AP1509 series operates at a switchin g
frequency of 150KHz thus allow smaller sized filter
components than what would be needed with lower frequenc y
switching regulators. Other features include a guaranteed
+

4% tolerance on output voltage under specified input voltage
and output load conditions, and +15% on the oscillator
frequency. The output version included fixed 3.3V, 5V, 12V,
and an adjustable type. The chips are available in a standard
8-lead SOP-8 package.

is down below 0.5V, the switching frequency

FB

Pin Assignments

V

1

IN

FB

SD

2

3

4

Output

(Top View)

AP1509

SOP-8L

GND

8

GND

7

GND

6

GND

5

Features

• Output Voltage: 3.3V, 5V, 12V and Adjustable Output
Version

• Adjustable Version Output Voltage Range, 1.23V to
18V+4%

• 150KHz +15% Fixed Switching Frequency

• Voltage Mode Non-Synchronous PWM Control

• Thermal-Shutdown and Current-Limit Protection

• ON/OFF Shutdown Control Input

• Operating Voltage can be up to 22V

• Output Load Current: 2A

• SOP-8L Packages

• Low Power Standby Mode

• Built-in Switching Transistor On Chip

• SOP-8L: Available in “Green” Molding Compound
(No Br, Sb)

• Lead Free Finish/ RoHS Compliant (Note 1)

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.

Applications

• Simple High-Efficiency Step-Down Regulator

• On-Card Switching Regulators

• Positive to Negative Converter

AP1509

Document number: DS31016 Rev. 4 - 2

1 of 13

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June 2010

© Diodes Incorporated

×

Typical Application Circuit

(1) Fixed Type Circuit

12V

DC Input

V

IN

C

IN

Capacitor

150KHz, 2A PWM BUCK DC/DC CONVERTER

FB

3

AP1509-

12

33

567

4

SD

GND

Output

8

GND

GNDGND

Schottky Diode

D1

L1

47uH

Inductor

AP1509

3.3V/2A

Output Load

Co

Capacitor

(2) Adjustable Type Circuit

12V

DC Input

C

IN

Capacitor

(3) Delay Start Circuit

12V

DC Input

C

DELAY

0.1uF

C

IN

Capacitor

R

10K

FB

3

GNDGNDGND

8

GND

= V

V

FB

Output

FB

= 1.23V

12

V

IN

AP1509

56 7

4

SD

V

OUT

R2 = 1K ~ 3K

FB

3

V

IN

12

AP1509

56 7

4

SD

DELAY

Output

8

GND

GNDGNDGND

(1 +

R1 1KR2 1K

D1

Schottky

Diode

R1

)

R2

R1 1KR2 1K

D1

Schottky

Diode

L1

39uH

Inductor

L1

39uH

Inductor

2.5V/2A

Output Load

Co

Capacitor

2.5V/2A

Output Load

Co

Capacitor

AP1509

Document number: DS31016 Rev. 4 - 2

2 of 13

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June 2010

© Diodes Incorporated

Pin Descriptions

Pin Name Description

VIN Operating voltage input

Output Switching output

GND Ground

FB Output voltage feedback control
SD ON/OFF Shutdown

Functional Block Diagram

AP1509

150KHz, 2A PWM BUCK DC/DC CONVERTER

SD

FB

Current

Source

bias

1.235V

Reference

+
_

Amp

2.5V

Regulator

Frequecy

compen-

sation

_

Comp

+

Start

up

150kH

z

OSC.

Comp

Comp

Pre-

driver

200mV

+
_

_

+

Thermal

Shutdown

220mV

2A

Switch

V

IN

Output

GND

AP1509

Document number: DS31016 Rev. 4 - 2

3 of 13

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© Diodes Incorporated

150KHz, 2A PWM BUCK DC/DC CONVERTER

Absolute Maximum Ratings

Symbol Parameter Rating Unit

ESD HBM Human Body Model ESD Protection

ESD MM Machine Model ESD Protection 200 V

VIN Supply Voltage +24 V
VSD ON/OFF Pin Input Voltage -0.3 to +18 V
VFB Feedback Pin Voltage -0.3 to +18 V

V

Output Voltage to Ground -1 V

OUT

PD Power Dissipation Internally Limited W

TST Storage Temperature -65 to +150

TJ Operating Junction Temperature -40 to +125

Recommended Operating Conditions

Symbol Parameter Min Max Unit

I

Output Current 0 2 A

OUT

VOP Operating Voltage 4.5 22 V

TA Operating Ambient Temperature -20 85

2

AP1509

KV

o

C

o

C

o

C

AP1509

Document number: DS31016 Rev. 4 - 2

4 of 13

www.diodes.com

June 2010

© Diodes Incorporated