A3958SLBTR Datasheet, PDF (1/10 Pages) Allegro MicroSystems – DMOS Full-Bridge PWM Motor Driver

A3958
DMOS Full-Bridge PWM Motor Driver
Features and Benefits
▪ ±2 A, 50 V continuous output rating
▪ Low r_DS(on) outputs (270 mΩ, typical)
▪ Programmable mixed, fast, and slow current-decay modes
▪ Serial interface controls chip functions
▪ Synchronous rectification for low power dissipation
▪ Internal UVLO and thermal-shutdown circuitry
▪ Crossover-current protection
Packages:
Package B, 24-pin DIP
with exposed tabs
Not to scale
Package LB, 24-pin SOIC
with internally fused pins
Description
Designed for pulse width modulated (PWM) current control of
DC motors, the A3958 is capable of continuous output currents
to ±2 A and operating voltages to 50 V. Internal fixed off-time
PWM current-control timing circuitry can be programmed via
a serial interface to operate in slow, fast, and mixed current-
decay modes.
PHASE and ENABLE input terminals are provided for use
in controlling the speed and direction of a DC motor with
externally applied PWM-control signals. The ENABLE input
can be programmed via the serial port to PWM the bridge in
fast or slow current decay. Internal synchronous rectification
control circuitry is provided to reduce power dissipation during
PWM operation.
Internal circuit protection includes thermal shutdown with
hysteresis, and crossover-current protection. Special power-up
sequencing is not required.
The A3958 is supplied in a choice of two power packages, a
24-pin plastic DIP with exposed thermal tabs (package suffix
‘B’), and a 24-pin SOIC with internally fused pins (package
suffix ‘LB’). In both cases, the power pins are at ground potential
and need no electrical isolation. Each package type is lead (Pb)
free, with 100% matte tin leadframe.
VDD
LOGIC
SUPPLY
Functional Block Diagram
VBB
+
LOAD
SUPPLY
CHARGE PUMP
BANDGAP
VDD
CREG
TSD
UNDER-
VOLTAGE &
FAULT DETECT
CHARGE
PUMP
BANDGAP
REGULATOR
VREG
MODE
PHASE
ENABLE
CONTROL LOGIC
OSC
FIXED OFF
PROGRAMMABLE ^BLANK
PWM TIMER
DECAY
CLOCK
DATA
STROBE
RANGE
SERIAL
PORT
29319.31F
SLEEP
MODE
ZERO
CURRENT
DETECT
CURRENT
SENSE
RANGE
REFERENCE
BUFFER &
DIVIDER
OUTA
OUTB
SENSE
CS
RS
REF
VREF
Dwg. FP-048