Features and Benefits
▪ Low R
DS(ON)
outputs
▪ Internal mixed current decay mode
▪ Synchronous rectification for low power dissipation
▪ Internal UVLO
▪ Crossover-current protection
▪ 3.3 and 5 V compatible logic supply
▪ Thin profile QFN and TSSOP packages
▪ Thermal shutdown circuitry
▪ Short-to-ground protection
▪ Shorted load protection
▪ Low current Sleep mode, < 10 μA
Description
The A4987 is a dual DMOS full-bridge stepper motor driver
with parallel input communication and overcurrent protection.
Each full-bridge output is rated up to 35 V and ±1 A. The A4987
includes fixed off-time pulse width modulation (PWM) current
regulators, along with 2- bit nonlinear DACs (digital-to-analog
converters) that allow stepper motors to be controlled in full,
half, and quarter steps. The PWM current regulator uses the
Allegro
™
patented mixed decay mode for reduced audible
motor noise, increased step accuracy, and reduced power
dissipation.
Internal synchronous rectification control circuitry is provided
to improve power dissipation during PWM operation.
The outputs are protected from shorted load and short-to-
ground events, which protect the driver and associated circuitry
from thermal damage or flare-ups. Other protection features
include thermal shutdown with hysteresis, undervoltage lockout
(UVLO) and crossover current protection. Special power-up
sequencing is not required.
The A4987 is supplied in two packages, a 24-contact QFN (ES)
and a 24-pin TSSOP (LP). Both packages have exposed thermal
pads for enhanced thermal performance. The 24-contact ES is
4 mm × 4 mm, with a nominal overall package height of 0.75
mm. The 24-pin LP is a TSSOP with 0.65 pitch and an overall
package height of ≤1.2 mm. Both packages are lead (Pb) free,
with 100% matte tin leadframe plating.
4987-DS, Rev. 5
DMOS Dual Full-Bridge PWM Motor Driver
With Overcurrent Protection
A4987
Typical Application Diagram
Microcontroller or
Controller Logic
V
DD
VREF
GND GND
PH2
IN12
SLEEP
IN11
PH1
IN02
IN01
VBB1
CP1 VCPVREG
VDD
ROSC
0.22 F
0.22 F
0.1 F0.1 F
100 F
CP2
VBB2
OUT1A
OUT1B
SENSE1
OUT2A
OUT2B
SENSE2
A4987
24-contact QFN
4 mm × 4 mm × 0.75 mm
(ES package)
Packages:
24-pin TSSOP
with exposed thermal pad
(LP Package)
Approximate size
