1FEATURES

2? Two Synchronous Buck Regulators

? 180° Out of Phase Operation

? 4.5V to 30V Input Range

? Power Good Function Monitors Ch.1

? 37μA Shutdown Current

? 0.04% (typical) Line and Load Regulation Error

? Current Mode Control With or Without a Sense

Resistor

? Independent Enable/Soft-start Pins Allow

Simple Sequential Startup Configuration.

? Configurable for Single Output Parallel

Operation. (See Figure 3).

? Adjustable Cycle-by-Cycle Current Limit

? Input Under-voltage Lockout

? Output Over-voltage Latch Protection

? Output Under-voltage Protection with Delay

? Thermal Shutdown

? Self Discharge of Output Capacitors When the

Regulator is OFF

? TSSOP package

APPLICATIONS

? Embedded Computer Systems

? High End Gaming Systems

? Set-top Boxes

? WebPAD

DESCRIPTION

The LM2642 consists of two current mode

synchronous buck regulator controllers with a

switching frequency of 300kHz.

The two switching regulator controllers operate 180°

out of phase. This feature reduces the input ripple

RMS current, thereby significantly reducing the

required input capacitance. The two switching

regulator outputs can also be paralleled to operate as

a dual-phase single output regulator.

The output of each channel can be independently

adjusted from 1.3 to VIN? maximum duty cycle. An internal 5V rail is also available externally for driving

bootstrap circuitry.

Current-mode feedback control assures excellent line

and load regulation and a wide loop bandwidth for

excellent response to fast load transients. Current is

sensed across either the Vds of the top FET or

across an external current-sense resistor connected

in series with the drain of the top FET. Current limit is

independently adjustable for each channel.

The LM2642 features analog soft-start circuitry that is

independent of the output load and output

capacitance. This makes the soft-start behavior more

predictable and controllable than traditional soft-start

circuits.

A PGOOD1 pin is provided to monitor the dc output

of channel 1. Over-voltage protection is available for both outputs. A UV-Delay pin is also available to

allow delayed shut off time for the IC during an output

under-voltage event.