FEATURES

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

DESCRIPTION

The Si9978 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 Si9978 is available in both standard and lead (Pb)-free,

24-pin wide-body SOIC (surface mount) packages, specified

to operate over the industrial (−40 to +85 C) temperature

range.