Description
The A3921 is a full-bridge controller for use with external
N-channel power MOSFETs and is specifically designed for
automotive applications with high-power inductive loads, such
as brush DC motors.
A unique charge pump regulator provides full (>10 V) gate
drive for battery voltages down to 7 V and allows the A3921
to operate with a reduced gate drive, down to 5.5 V.
A bootstrap capacitor is used to provide the above-battery
supply voltage required for N-channel MOSFETs. An internal
charge pump for the high-side drive allows DC (100% duty
cycle) operation.
The full bridge can be driven in fast or slow decay modes using
diode or synchronous rectification. In the slow decay mode,
current recirculation can be through the high-side or the low-
side FETs. The power FETs are protected from shoot-through
by resistor adjustable dead time.
Integrated diagnostics provide indication of undervoltage,
overtemperature, and power bridge faults, and can be
configured to protect the power MOSFETs under most short
circuit conditions.
The A3921 is supplied in a 28-pin TSSOP power package with
an exposed thermal pad (suffix LP). This package is lead (Pb)
free, with 100% matte-tin leadframe plating.
3921-DS
Features and Benefits
▪ High current gate drive for N-channel MOSFET full bridge
▪ High-side or low-side PWM switching
▪ Charge pump for low supply voltage operation
▪ Top-off charge pump for 100% PWM
▪ Cross-conduction protection with adjustable dead time
▪ 5.5 to 50 V supply voltage range
▪ Integrated 5 V regulator
▪ Diagnostics output
▪ Low current sleep mode
Automotive Full Bridge MOSFET Driver
Package: 28-pin TSSOP with exposed
thermal pad (suffix LP)
Typical Application
Not to scale
A3921
A3921
VBAT
PWM
Direction
Fault Flags
