POWER MANAGEMENT

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SC1405D

High Speed Synchronous Power

MOSFET Smart Driver

PRELIMINARY

Features

Applications

Revision: June 8, 2005

Typical Application Circuit

Description

The SC1405D is a Dual-MOSFET Driver with an internal

Overlap Protection Circuit to prevent shoot-through. Each

driver is capable of driving a 3000pF load in 15ns rise/

fall time and has ULTRA-LOW propagation delay from in-

put transition to the gate of the power FETs. Adaptive

Overlap Protection circuit ensures that the synchronous

FET does not turn on until the top FET source has reached

a voltage low enough to prevent shoot-through. The de-

lay between the bottom gate going low to the top gate

transitioning high is externally programmable via a ca-

pacitor to minimize dead time. The bottom FET may be

disabled at light loads by keeping S_MOD low to trigger

asynchronous operation, thus saving the bottom FET’s

gate drive current and inductor ripple current.

An internal voltage reference allows threshold adjustment

for an Output Over-Voltage protection circuitry, indepen-

dent of the PWM controller. The device provides over-

voltage protection independent of the PWM feedback

loop with a unique “adaptive OVP” comparator which re-

jects noise but responds quickly to a true OVP situation.

Under-Voltage-Lock-Out circuit is included to guarantee

that both driver outputs are off when Vcc is less than or

equal to 4.4V (typ) at supply ramp up (4.35V at supply

ramp down). A CMOS output provides status indication

of the 5V supply. A low enable input places the IC in stand-

by mode, reducing supply current to less than 10µA.

Fast rise and fall times (15ns with 3000pf load)

14ns max. Propagation delay (BG going with low)

Adaptive and programmable shoot-through

protection

Adaptive overvoltage protection

Wide input voltage range (4.5V - 25V)

Programmable delay between FETs

Power saving asynchronous mode control

Output overvoltage protection/overtemp shutdown

Under-Voltage lock-out and power ready signal

Less than 10µA stand-by current (EN=low)

Power ready output signal

High frequency (to 1.2MHz) operation allows use of

small inductors and low cost caps in place of

electrolytics

TSSOP-14 package

High Density/Fast transient microprocessor power

supplies

Motor Drives/Class-D amps

High efficiency portable computers