A4984_12 Datasheet, PDF (1/22 Pages) Allegro MicroSystems – DMOS Microstepping Driver with Translator And Overcurrent Protection

A4984
DMOS Microstepping Driver with Translator
And Overcurrent Protection
Features and Benefits
▪ Low R_DS(ON) outputs
▪ Automatic current decay mode detection/selection
▪ Mixed and Slow current decay modes
▪ 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
▪ No smoke no fire (NSNF) compliance (ET package)
Packages:
24-contact QFN
with exposed thermal pad
4 mm × 4 mm × 0.75 mm
(ES package)
32-contact QFN
with exposed thermal pad
5 mm × 5 mm × 0.90 mm
(ET package)
Description
The A4984 is a complete microstepping motor driver with
built-in translator for easy operation. It is designed to operate
bipolar stepper motors in full-, half-, quarter-, and eighth-step
modes. Step modes are selectable by MSx logic inputs. It has
an output drive capacity of up to 35 V and ±2 A. The A4984
includes a fixed off-time current regulator which has the ability
to operate in Slow or Mixed decay modes.
The ET package meets customer requirements for no smoke
no fire (NSNF) designs by adding no-connect pins between
critical output, sense, and supply pins. So, in the case of a
pin-to-adjacent-pin short, the device does not cause smoke
or fire. Additionally, the device does not cause smoke or fire
when any pin is shorted to ground or left open.
The translator is the key to the easy implementation of the
A4984. Simply inputting one pulse on the STEP input drives
the motor one microstep. There are no phase sequence tables,
high frequency control lines, or complex interfaces to program.
The A4984 interface is an ideal fit for applications where a
complex microprocessor is unavailable or is overburdened.
During stepping operation, the chopping control in the A4984
automatically selects the current decay mode, Slow or Mixed.
Continued on the next page…
24-pin TSSOP
with exposed thermal pad
(LP Package)
Microcontroller or
Controller Logic
Typical Application Diagram
V_DD
0.22 μF
0.1 μF
0.1 μF
0.22 μF
5 kΩ
VREG ROSC CP1
VDD
CP2
VCP _VBB1
VBB2
SLEEP
STEP
MS1
MS2
DIR
ENABLE
RESET
VREF
A4984
OUT1A
OUT1B
SENSE1
GND
OUT2A
GND
OUT2B
SENSE2
4984-DS, Rev. 4
100 μF