General Description

The LM2655 is a current-mode controlled PWM step-down

switching regulator. It has the unique ability to operate in

synchronous or asynchronous mode. This gives the designer

flexibility to choose between the high efficiency of

synchronous operation, or the low solution cost of asynchronous

operation. Along with flexibility, the LM2655 offers high

power density with the small footprint of a TSSOP-16 package.

High efficiency (>90%) is obtained through the use of an

internal low ON-resistance (33mΩ) MOSFET, and an external

N-Channel MOSFET. This feature, together with its low

quiescent current, makes the LM2655 an ideal fit in portable

applications.

Integrated in the LM2655 are all the power, control, and drive

functions for asynchronous operation. In addition, a low-side

driver output allows easy synchronous operation. The IC

uses patented current sensing circuitry that eliminates the

external current sensing resistor required by other currentmode

DC-DC converters. A programmable soft-start feature

limits start up current surges and provides a means of sequencing

multiple power supplies.

Features

Ultra-high efficiency up to 96%

4V to 14V input voltage range

Internal high-side MOSFET with low RDS(ON) = 0.033Ω

300 kHz fixed frequency internal oscillator

Low-side drive for synchronous operation

Guaranteed less than 12 μA shutdown current

Patented current sensing for current mode control

Programmable soft-start

Input undervoltage lockout

Output overvoltage shutdown protection

Output undervoltage shutdown protection

Thermal Shutdown

16-pin TSSOP package

Applications

Hard disk drives

Internet appliances

TFT monitors

Computer peripherals

Battery powered devices