April 2009

1

M9999-040609

MIC2169A

Micrel

MIC2169A

500kHz PWM Synchronous Buck Control IC

General Description

The MIC2169A is a high-efficiency, simple to use 500kHz

PWM synchronous buck control IC housed in a small MSOP-

10 package.The MIC2169Aallows compact DC/DC solutions

with a minimal external component count and cost.

The MIC2169A operates from a 3V to 14.5V input, without

the need of any additional bias voltage. The output voltage

can be precisely regulated down to 0.8V. The adaptive all

N-Channel MOSFET drive scheme allows efficiencies over

95% across a wide load range.

The MIC2169A senses current across the high-side N-

Channel MOSFET, eliminating the need for an expensive

and lossy current-sense resistor. Current limit accuracy is

maintained by a positive temperature coefficient that tracks

and space are saved by the internal in-rush-current limiting

digital soft-start.

The MIC2169A is available in a 10-pin MSOP package, with

a wide junction operating range of –40°C to +125°C.

All support documentation can be found on Micrel’s web site

at www.micrel.com.

Typical Application

2.5H

3.3V

VDD

COMP/EN

VIN

CS

FB

GND

LSD

BST

1k

10k

4k

3.24k

4.7F

100F

0.1F

0.1F

100nF

IRF7821

SD103BWS

IRF7821

150pF

HSD

VSW

5

MIC2169A

0.1µF

1000pF

1.4

150F x 2

2

MIC2169A Adjustable Output 500kHz Converter

Features

• 3V to 14.5V input voltage range

• Adjustable output voltage down to 0.8V

• Up to 95% efficiency

• 500kHz PWM operation

• Adjustable current limit senses high-side N-Channel

MOSFET current

• No external current-sense resistor

• Adaptive gate drive increases efficiency

• Overvoltage protection protects the load in fault

conditions

• Dual mode current limit speeds up recovery time

• Hiccup mode short-circuit protection

• Internal soft-start

• Dual function COMP and EN pin allows low-power shut-

down

• Small size MSOP 10-lead package

Applications

• Point-of-load DC/DC conversion

• Set-top boxes

• Graphic cards

• LCD power supplies

• Telecom power supplies

• Networking power supplies

• Cable modems and routers

Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

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MIC2169A Efficiency