POWER MANAGEMENT

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SC1211

Synchronous MOSFET Driver

Features

Applications

February 24, 2003

put driver designed to drive high-side and low-side

MOSFETs in a synchronous Buck converter. These

drivers combined with Combi-Sense PWM controllers,

such as Semtech SC2643VX or SC2643, provide a

cost effective multi-phase voltage regulator for advanced

microprocessors

current for peak current mode control of voltage regula-

tor without using sensing resistor. It provides the follow-

ing advantages:

- No costly precision sensing resistor

- Lossless current sensing

- High level noise free signal

- Fast response

- Suitable for wide range of duty cycle

- Only two small signal components (third optional)

The detailed explanation of the technique can be found

in the Applications Information section.

A 30ns max propagation delay from input transition to

the gate of the power FET’s guarantees operation at high

switching frequencies. Internal overlap protection circuit

prevents shoot-through from Vin to PGND in the main

and synchronous MOSFETs. The adaptive overlap pro-

tection circuit ensures the bottom FET does not turn on

until the top FET source has reached 1V, to prevent cross-

conduction.

8.5V gate drive provides optimum enhancement of

MOSFETs at minimum driver and MOSFET switching loss.

High current drive capability allows fast switching, thus

reducing switching losses at high (up to 1.5MHz) frequen-

cies without causing thermal stress on the driver.

Under-voltage-lockout and over-temperature shutdown

features are included for proper and safe operation.

Timed latches and improved robustness are built into

the housekeeping functions such as the Under Voltage

Lockout and adaptive Shoot-through protection circuitry

to prevent false triggering and to assure safe operation.

The SC1211 is offered in a Power SOIC-8L package.

gate drive

shoot-through protection

load)

of small inductors and low cost ceramic capacitors

processor power supplies

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Description