A4992 Datasheet, PDF (1/29 Pages) Allegro MicroSystems – Automotive Stepper Driver

A4992
Automotive Stepper Driver
Features and Benefits
• Low R_DS(on) outputs, 0.5 Ω source and sink typical
• Continuous operation at high ambient temperature
• 3.5 to 50 V supply operation
• Adaptive mixed current decay
• Synchronous rectification for low power dissipation
• Internal overvoltage and undervoltage lockout
• Hot warning and overtemperature shutdown
• Crossover-current protection
• Short circuit and open load diagnostics
• Stall detect features
• Configurable through serial interface
Applications:
• Automotive stepper motors
• Engine management
• Headlamp positioning
Package: 20-pin TSSOP with exposed
thermal pad (suffix LP)
Not to scale
Description
The A4992 is a flexible microstepping motor driver with
integrated phase current control and a built-in translator for
easy operation. It is a single chip solution designed to operate
bipolar stepper motors in full, half, quarter, eighth, and
sixteenth step modes, at up to 28 V. At power-on the A4992
is configured to drive most small stepper motors with simple
step and direction inputs.
The current regulator operates with fixed frequency PWM. It
uses adaptive mixed current decay to reduce audible motor
noise and increase step accuracy.
The current in each phase of the motor is controlled through a
DMOS full bridge using synchronous rectification to improve
power dissipation. Internal circuits and timers prevent cross-
conduction and shoot-through when switching between
high‑side and low‑side drives.
The outputs are protected from short circuits. Features
for low load current and stalled rotor detection are
included. Chip level protection includes hot thermal
warning, overtemperature shutdown, and overvoltage and
undervoltage lockout.
An optional serial interface mode, using the STEP, DIR, and
MS inputs, can be used to configure several motor control
parameters and diagnostics.
The A4992 is supplied in a 20-pin TSSOP power package with
an exposed thermal pad (package type LP). This package is
lead (Pb) free with 100% matte-tin lead frame plating.
Typical Application Diagram
Logic
Supply
Micro-
controller
or
ECU
CP1 CP2
REF
VCP VBB
OAP
STEP
DIR
A4992
OAM
MS
RESETn
OBP
DIAG
VREG
AGND
OBM
SENSA
SENSB
PGND
Automotive
12 V Power Net
Stepper
Motor
A4992-DS, Rev. 1