August 1996

PRELIMINARY

ML4895

Synchronous Buck Controller

1

FEATURING

Extended

Commercial

Temperature

Range

-20˚C to 70˚C

for Portable

Handheld

Equipment

BLOCK DIAGRAM

FEATURES

s

Regulation to ±3% maximum

s

Adjustable output synchronous buck (2.5V to 4V)

s

Wide input voltage range (5.9V to 15V)

s

Power conversion efficiencies of >90% over 3 decades

of output current

s

Integrated antishoot-through logic

s

Shutdown control provides load isolation and

minimum sleep mode power consumption

s

Low shutdown current

P DRV

N DRV

VOUT

2.5V - 4V

+

–

ISENSE

VFB

8

1

FROM SYSTEM

POWER

MANAGEMENT

GND

VREG

BIAS

CIRCUITS

SHDN

5

7

6

3

2

VIN

5.9V - 15V

4

SLEEP

LOGIC

GENERAL DESCRIPTION

The ML4895 synchronous buck controller has been

designed to provide high efficiency DC/DC conversion for

portable products. The ML4895 can deliver a user

programmable 2.5V to 4V output from input voltages of

5.9V to 15V.

The ML4895 drives external P- and N-channel MOSFETs

in a synchronous buck topology, allowing an overall

conversion efficiency of greater than 90% over an output

current range exceeding three decades, with an output

current capability of up to 5A.

The regulator can be disabled via the SHDN pin. While

disabled, the output of the regulator is completely

isolated from the circuit’s input supply, and the supply

current is reduced to less than 5µA to help extend battery

life.