April 2005

1

M9999-062205

MIC2168A

MIC2168A

1MHz PWM Synchronous Buck Control IC

General Description

The MIC2168Ais a high-efficiency, simple to use 1MHz PWM

synchronous buck control IC housed in a small MSOP-10

package. The MIC2168A allows compact DC/DC solutions

with a minimal external component count and cost.

The MIC2168A 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 MIC2168A 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

DS(ON)

DS(ON)

digital soft-start.

The MIC2168A 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

1.2µH

3.3V

VDD

COMP/EN

VIN

CS

FB

GND

LSD

BST

1kΩ

10kΩ

4kΩ

3.24kΩ

4.7µF

100µF

0.1µF

100nF

1000nF

2Ω

IRF7821

SD103BWS

IRF7821

100pF

HSD

VSW

MIC2168A

150µF x 2

MIC2168A Adjustable Output 1MHz Converter

Features

• 3V to 14.5V input voltage range

• Adjustable output voltage down to 0.8V

• Up to 95% efficiency

• 1MHz PWM operation

• Adjustable current-limit senses high-side N-Channel

MOSFET current

• No external current sense resistor

• Adaptive gate drive increases efficiency

• Ultra-fast response with hysteretic transient recovery

mode

• 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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MIC2168 Efficiency

V

V