A3985 Datasheet, PDF (1/15 Pages) Allegro MicroSystems – Digitally Programmable Dual Full-Bridge MOSFET Driver

A3985
Digitally Programmable
Dual Full-Bridge MOSFET Driver
Features and Benefits
▪ Serial interface for full digital control
▪ Dual full-bridge gate drive for N-channel MOSFETs
▪ Dual 6-bit DAC current reference
▪ Operation over 12 to 50 V supply voltage range
▪ Synchronous rectification
▪ Cross-conduction protection
▪ Adjustable mixed decay
▪ Fixed off-time PWM current control
▪ Low-current idle mode
Package: 38 pin TSSOP (suffix LD)
Description
The A3985 is a flexible dual full-bridge gate driver suitable
for driving a wide range of higher power industrial bipolar 2-
phase stepper motors or 2-phase brushless dc motors. It can
also be used to drive two individual torque motors or solenoid
actuators. Motor power is provided by external N-channel power
MOSFETs at supply voltages from 12 to 50 V.
Full digital control is provided by two serially-accessible
registers that allow programming of off-time, blank-time,
dead-time, mixed decay ratios, synchronous rectification,
master clock source selection, and division ratio and idle
mode. All internal timings are derived from a master clock
that can be generated on-chip or provided by an external
clock such as the system clock of the master controller. A
programmable divider allows for a wide range of external
system clock frequencies.
The internal fixed off-time PWM current-control timing is
programmed via the serial interface to operate in slow, fast,
and mixed current-decay modes. The desired load-current level
and direction is set via the serial port with a direction bit and
two 6-bit linear DACs in conjunction with a reference voltage.
The seven bits of control allow maximum flexibility in torque
Approximate size
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Typical Application
3985-DS