POWER MANAGEMENT

1

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SC1405B

High Speed Synchronous Power

MOSFET Smart Driver

Features

Applications

Revision: January 13, 2004

Typical Application Circuit

Description

The SC1405B 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 FET’s. 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 inter-

nal voltage reference allows threshold adjustment for

an Output Over-Voltage protection circuitry, independent

of the PWM controller.

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.

SC1405B is offered in a high pitch (.025” lead spacing)

TSSOP package.

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

14ns max. Propagation delay (BG going low)

Adaptive and programmable shoot-through

protection

Wide input voltage range (4.5-25V)

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)

Improved drive version of SC1405TS

High frequency (to 1.2MHz) operation allows use of

small inductors and low cost capacitors in place of

electrolytics

High Density/Fast transient microprocessor power

supplies

Motor Drives/Class-D amps

High efficiency portable computers

+

(20KHz-1MHz)

2.2

+

10uF,6.3V

MTB75N03

.1uF

SC1405

13

4

3

2

1

14

6

5

10

7

9

11

12

8

5817

MTB75N03

1.7V@30A

INPUT POWER, 5-20V

+

>>

75A,30V

75A,30V

<<< Output Feedback to PWM

Controller

+

+

Over-Voltage Sense

47pF

.22uF

Vcc

+

<<

2.2

PWM IN

<< P_READY

+

DSPS_DR