Si9978DW

Vishay Siliconix

FaxBack 408-970-5600, request 70011

S-60752—Rev. D, 05-Apr-99

www.siliconix.com

1

Configurable H-Bridge Driver

FEATURES

DESCRIPTION

The Si9978DW is an integrated driver for an n-channel

MOSFET H-bridge. The mode control allows operation as

either

a

full

H-bridge

driver

or

as

two

independent

half-bridges. The DIR/PWM input configuration allows easy

implementation of either sign/magnitude or anti-phase PWM

drive schemes for full H-bridges. Schmitt triggers on the

inputs provide logic signal compatibility and hysteresis for

increased noise immunity. An internal low-voltage regulator

allows the device to be powered directly from a system supply

of 20 to 40 volts. All n-channel gates are driven directly from

low-impedance

outputs.

The

addition

of

one

external

capacitor per half-bridge allows internal circuitry to level shift

both the power supply and logic signal for the high-side

n-channel gate drives. Internal charge pumps replace leakage

current lost in the high-side driver circuits to provide “static”

(dc) operation in any output condition. Protection features

include an undervoltage lockout, cross-conduction prevention

logic, and overcurrent monitors.

The Si9978DW is available in the 24-pin wide-body SOIC

(surface mount) package, specified to operate over the

industrial (-40 to +85

°C) temperature range.

FUNCTIONAL BLOCK DIAGRAM

• H-Bridge or Dual Half-Bridge Operation

• 20- to 40-V Supply

• Static (dc) Operation

• Cross-Conduction Protected

• Current Limit

• Undervoltage Lockout

• ESD Protected

• Fault Output

Si9978