A3983
DMOS Microstepping Driver with Translator
Features and Benefits
▪ Low RDS(ON) outputs
Description
The A3983 is a complete microstepping motor driver with
▪ Automatic current decay mode detection/selection
▪ Mixed and Slow current decay modes
▪ Synchronous rectification for low power dissipation
▪ Internal UVLO and thermal shutdown circuitry
▪ Crossover-current protection
built-in translator for easy operation. It is designed to operate
bipolar stepper motors in full-, half-, quarter-, and eighth-step
modes, with an output drive capacity of up to 35 V and ±2 A.
The A3983 includes a fixed off-time current regulator which
has the ability to operate in Slow or Mixed decay modes.
The translator is the key to the easy implementation of the
A3983. Simply inputting one pulse on the STEP input drives
the motor one microstep. There are no phase sequence tables,
highfrequencycontrollines,orcomplexinterfacestoprogram.
The A3983 interface is an ideal fit for applications where a
complex microprocessor is unavailable or is overburdened.
Package: 24-pin TSSOP with exposed thermal pad
(suffix LP)
The chopping control in the A3983 automatically selects the
current decay mode (Slow or Mixed). When a signal occurs at
the STEP input pin, the A3983 determines if that step results
in a higher or lower current in each of the motor phases. If
the change is to a higher current, then the decay mode is set to
Slow decay. If the change is to a lower current, then the current
decay is set to Mixed (set initially to a fast decay for a period
amounting to 31.25% of the fixed off-time, then to a slow
decay for the remainder of the off-time). This current decay
Not to scale
Continued on the next page…
Functional Block Diagram
0.1 μF
CP2
0.22 μF
CP1
VREG
ROSC
VDD
REF
Current
Regulator
Charge
Pump
OSC
VCP
0.1 μF
DMOS Full Bridge
VBB1
DAC
OUT1A
OUT1B
PWM Latch
Blanking
Mixed Decay
SENSE1
VBB2
STEP
DIR
Gate
Drive
RS1
DMOS Full Bridge
RESET
Control
Logic
Translator
MS1
MS2
OUT2A
OUT2B
PWM Latch
Blanking
Mixed Decay
ENABLE
SLEEP
SENSE2
RS2
DAC
VREF
26184.29B