MP8709

High Efficiency 4A, 21V, 500kHz

Synchronous Step-down Converter

MP8709 Rev. 1.01

www.MonolithicPower.com

1

12/14/2011

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© 2011 MPS. All Rights Reserved.

The Future of Analog IC Technology

DESCRIPTION

The MP8709 is a high frequency synchronous

rectified step-down switch mode converter with

built in power MOSFETs. It offers a very

compact solution to achieve 4A continuous

output current over a wide input supply range

with excellent load and line regulation. The

MP8709 has synchronous mode operation for

higher efficiency over output current load range.

MP8709 achieves low EMI signature with well

controlled switching edges.

Current mode operation provides fast transient

response and eases loop stabilization.

Full protection features include OCP and

thermal shut down.

The MP8709 requires a minimum number of

readily available standard external components

and is available in a space saving 8-pin SOIC

package with an exposed pad.

FEATURES

• Wide 4.5V to 21V Operating Input Range

• 4A Output Current

• Low Rds(on) Internal Power MOSFETs

• Low-EMI Switching Speed Technology

• High Efficiency Synchronous Mode Operation

• Fixed 500kHz Switching Frequency

• Sync from 300kHz to 2MHz External Clock

• Internal Compensation

• Integrated Bootstrap Diode

• OCP Protection (Hiccup Mode)

• Thermal Shutdown

• Output Adjustable from 0.8V

• Available in a Thermally Enhanced 8-pin SOIC

package

APPLICATIONS

•

Notebook Systems and I/O Power

•

Networking Systems

•

Digital Set Top Boxes

•

Personal Video Recorders

•

Flat Panel Television and Monitors

•

Distributed Power Systems

All MPS parts are lead-free and adhere to the RoHS directive. For MPS green

status, please visit MPS website under Products, Quality Assurance “MPS”

and “The Future of Analog IC Technology” are Registered Trademarks of

Monolithic Power Systems, Inc.

TYPICAL APPLICATION

C1

22uF

MP8709

SW

GND

FB

EN/SYNC

IN

BST

VCC

C4

0.1uF

R2

10k

Rt

56k

R1

4.99k

L1

1.8uH

C2

47uF

C3

0.1uF

VIN

VOUT 1.2V

ON/OFF

6

8

4

2,3

1

7

5

21

Efficiency

OUTPUT CURRENT (A)

0

10

20

30

40

50

60

70

80

90

100

0 0.5

1 1.5

2 2.5

3 3.5

4