October 2003

1

M0334-102203

MIC4682

Micrel

MIC4682

Precision Current Limit SO-8 SuperSwitcher™ Buck Regulator

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com

General Description

The MIC4682 is an easy-to-use step-down (buck) switch-

mode voltage regulator. It features a programmable current

limit that allows 10% current limit accuracy over its full

operating temperature range. The precision current limit

makes the MIC4682 ideal for constant-voltage constant-

current applications, such as simple battery chargers. The

precision current limit also gives designers the ability to set

the maximum output current below the saturation current

rating of the inductor. This allows the use of the smallest

possible inductors for a given application, saving valuable

space and cost.

The MIC4682 is a very robust device. Its 4V to 34V input

voltage range allows the MIC4682 to safely be used in

applications where voltage transients may be present. Addi-

tional protection features include cycle-by-cycle current lim-

iting and over-temperature shutdown. The MIC4682 is avail-

able in a thermally optimized power SO-8 package that allows

it to achieve 2A of continuous output current.

The MIC4682 requires a minimum number of external com-

ponents and can operate using a standard series of induc-

tors. Compensation is provided internally for fast transient

response and ease of use. The MIC4682 is available in the 8-

lead power SOP with a –40

°C to +125°C junction tempera-

ture range.

Typical Application

SW

L1

68

µH

IN

FB

ISET

SHDN

C2

220

µF

10V

R1

3.01k

R3

10M

R4

16.2k

R2

976

Ω

5V/1A

MIC4682

C1

10

µF

50V

(x2)

+7.5V to +34V

2, 6, 7

1

8

5

4

D1

B240

GND

3

0

1

2

3

4

5

6

0

0.5

1

1.5

2

CURRENT LIMIT (A)

MIC4682 Current Limit

Characteristics

V

Constant Current/Constant Voltage Li Ion Battery Charger

Features

• Programmable output current limit

• 10% accuracy over temperature

• Wide 4V to 34V operating input voltage range

• Fixed 200kHz PWM operation

• Power SO-8 package allows 2A continuous output

current

• All surface mount solution

• Internally compensated

• Less than 1

µA typical shutdown-mode current

• Thermal shutdown protection

Applications

• Battery chargers

• White LED drivers

• Constant voltage constant current step-down converters

• Simple step-down regulator with precise current limit

• USB power supplies

SuperSwitcher is a trademark of Micrel, Inc.