April 22, 2004

1

M9999-042204

MIC2182

Micrel

MIC2182

High-Efficiency Synchronous Buck Controller

General Description

Micrel’s MIC2182 is a synchronous buck (step-down) switch-

ing regulator controller. An all N-channel synchronous archi-

tecture and powerful output drivers allow up to a 20A output

current capabilty. The PWM and skip-mode control scheme

allows efficiency to exceed 95% over a wide range of load

current, making it ideal for battery powered applications, as

well as high current distributed power supplies.

The MIC2182 operates from a 4.5V to 32V input and can

operate with a maximum duty cycle of 86% for use in low-

dropout conditions. It also features a shutdown mode that

reduces quiescent current to 0.1

µA.

The MIC2182 achieves high efficiency over a wide output

current range by automatically switching between PWM and

skip mode. Skip-mode operation enables the converter to

maintain high efficiency at light loads by turning off circuitry

pertaining to PWM operation, reducing the no-load supply

current from 1.6mA to 600

µA. The operating mode is inter-

nally selected according to the output load conditions. Skip

mode can be defeated by pulling the PWM pin low which

reduces noise and RF interference.

The MIC2182 is available in a 16-pin SOP (small-outline

package) and SSOP (shrink small-outline package) with an

operating range from –40

°C to +85°C.

Typical Application

VDD

BST

C6

0.1

µF

R1

2k

R7

100k

4.5V to 30V*

3.3V/4A

GND

C2

2.2nF

C4

1nF

C3

0.1

µF

C5

0.1

µF

C1

0.1

µF

C9

4.7

µF

16V

C11

22uf

35V

x2

D2

SD103BWS

Q2*

Si4884

D1

B140

C7

220uf

10V

×2

L1

10

µH

R2

0.02

Ω

Q1*

Si4884

HSD

VSW

LSD

PGND

CSH

VOUT

VREF

SGND

GND

MIC2182-3.3BSM

VIN

EN/UVLO

SS

PWM

COMP

SYNC

C13, 1nF

10

6

2

1

3

5

4

7

9

8

12

13

15

16

14

11

* 30V maximum input voltage limit is due

to standard 30V MOSFET selection.

See “Application Information” section for

5V to 3.3V/10A and other circuits.

4.5V–30V* to 3.3V/4A Converter

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

Features

• 4.5V to 32V Input voltage range

• 1.25V to 6V Output voltage range

• 95% efficiency

• 300kHz oscillator frequency

• Current sense blanking

• 5

Ω impedance MOSFET Drivers

• Drives N-channel MOSFETs

• 600

µA typical quiescent current (skip-mode)

• Logic controlled micropower shutdown (I

• Current-mode control

• Cycle-by-cycle current limiting

• Built-in undervoltage protection

• Adjustable undervoltage lockout

• Easily synchronizable

• Precision 1.245V reference output

• 0.6% total regulation

• 16-pin SOP and SSOP packages

• Frequency foldback overcurrent protection

• Sustained short-circuit protection at any input voltage

• 20A output current capability

Applications

• DC power distribution systems

• Notebook and subnotebook computers

• PDAs and mobile communicators

• Wireless modems

• Battery-operated equipment