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