LM2722

High Speed Synchronous/Asynchronous MOSFET Driver

General Description

The LM2722, part of the LM2726 family, is designed to be

used with multi-phase controllers. This part differs from the

LM2726 by changing the functionality of the SYNC_EN pin

from a whole chip enable to a low side MOSFET enable. As

a result, the SYNC_EN pin now provides control between

Synchronous and Asynchronous operations. Having this

control can be advantageous in portable systems since

Asynchronous operations can be more efficient at very light

loads.

The LM2722 drives both top and bottom MOSFETs in a

push-pull structure simultaneously. It takes a logic level

PWM input and splits it into two complimentary signals with

a

typical

20ns

dead

time

in

between. The

built-in

cross-conduction protection circuitry prevents the top and

bottom

FETs

from

turning

on

simultaneously.

The

cross-conduction protection circuitry detects both the driver

outputs and will not turn on a driver until the other driver

output is low. With a bias voltage of 5V, the peak sourcing

and sinking current for each driver of the LM2722 is typically

3A. In an SO-8 package, each driver is able to handle 50mA

average current. Input UVLO (Under-Voltage-Lock-Out)

forces both driver outputs low to ensure proper power-up

and power-down operation. The gate drive bias voltage

needed by the high side MOSFET is obtained through an

external bootstrap. Minimum pulse width is as low as 55ns.

Features

n

Synchronous or Asynchronous Operation

n

Adaptive shoot-through protection

n

Input Under-Voltage-Lock-Out

n

Typical 20ns internal delay

n

Plastic 8-pin SO package

Applications

n

Driver for LM2723 Intel Mobile Northwood CPU core

power supply.

n

High Current DC/DC Power Supplies

n

High Input Voltage Switching Regulators

n

Fast Transient Microprocessors

Typical Application

20028901

Note: National is an Intel Mobile Voltage Positioning (IMVP) licensee.

December 2001

© 2001 National Semiconductor Corporation

DS200289

www.national.com