FEATURES

• Ultra High Efficiencies (95% possible)

• High Efficiency Over a 3A to Milliamperes

Load Range

• Synchronous Switching of Internal NMOS

Power FETs

• Wide Input Voltage Range (4.5V to 18V)

• Output Voltage Adjustable from 1.5V to 16V

• Automatic Low-Power Sleep Mode

• Logic-Controlled Micropower Shutdown (IQSD ≤

25 μA)

• Frequency Adjustable up to 300 kHz

• Frequency Synchronization with External

Signal

• Programmable Soft-Start

• Short-Circuit Current Limiting

• Thermal Shutdown

• Available in 24-lead Small-Outline Package

APPLICATIONS

• Notebook and Palmtop Personal Computers

• Portable Data Terminals

• Modems

• Portable Instruments

• Global Positioning Devices (GPSs)

• Battery-Powered Digital Devices

DESCRIPTION

The LM2650 is a step-down DC/DC converter

featuring high efficiency over a 3A to milliamperes

load range. This feature makes the LM2650 an ideal

fit in battery-powered applications that demand long

battery life in both run and standby modes.

The LM2650 also features a logic-controlled

shutdown mode in which it draws at most 25μA from

the input power supply.

The LM2650 employs a fixed-frequency pulse-width

modulation (PWM) and synchronous rectification to

achieve very high efficiencies. In many applications,

efficiencies reach 95%+ for loads around 1A and

exceed 90% for moderate to heavy loads from 0.2A

to 2A.

A low-power hysteretic or sleep mode keeps

efficiencies high at light loads. The LM2650 enters

and exits sleep mode automatically as the load

crosses sleep in and sleep out thresholds. The

LM2650 provides nodes for programming both

thresholds via external resistors. A logic input allows

the user to override the automatic sleep feature and

keep the LM2650 in PWM mode regardless of the

load level.

An optional soft-start feature limits current surges

from the input power supply at start up and provides

a simple means of sequencing multiple power

supplies.