A4983 DMOS MICROSTEPPING DRIVER WITH TRANSLATOR
- click image to enlarge
The A4983 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, eighth, and sixteenth step modes, with an output drive capacity of up to 35 V and ±2A.
The A4983 includes a fixed off-time PWM current regulator that operates in both slow or mixed decay modes.
The translator is the key to the easy implementation of the A4983. Simply inputting one pulseon the STEP input drives the motor one microstep. There are no phase sequence tables, high-frequency control lines, or complex interfaces to program. The A4983 interface is an ideal fit for applications where a complex microprocessor is unavailable or is overburdened.
The chopping control in the A4983 automatically selects the current decay mode (slow or mixed). When a signal occurs at the STEP input pin, the A4983 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 control scheme results in reduced audible motor noise, increased step accuracy, and reduced power dissipation. The synchronous rectification control circuitry is provided to improve power dissipation during PWM operation.
Internal protection circuitry includes: thermal shutdown with hysteresis, undervoltage lockout, and crossover-current protection. Special power-up sequencing is not required.
The A4983 is supplied in a 28-lead 5 mm x 5 mm x 0.9 mm (nominal) QFN package with exposed thermal pad (suffix ET). The package is lead (Pb) free (suffix -T), with 100% matte tin plated leadframe.
Features and Benefits
- 35 V, ±2 A rating
- The ±2 A rating is 0.5 A above most competitors.
- Additional safety margin for high reliability designs.
- Small 28 lead 5 mm x 5 mm x 0.9 mm (nominal)
- QFN package
- Less than 1/3 the PC board space of our closest competitor.
- In many applications PCB space is tight so smaller is better.
- Step and Direction input interface
- Two control lines versus eight to 10 or more control lines for competing devices.
- Additional I/O lines can add to system cost.
- Commutation tables are not required.
- Five microstepping resolution settings
- Full, half, quarter, eighth, and sixteenth microstep resolutions for maximum flexibility.
- Synchronous rectification
- Reduces power dissipation and can eliminate the need for expensive Schottky diodes.
- Low RON DMOS outputs
- Reduces power dissipation.
- Can achieve higher average output current due to the lower die temperature rise.
- Automatic - slow and mixed decay
- Improved microstepping accuracy; reduced audible noise;
- Mixed decay mode is an Allegro-patented feature.
- Less than 10 μA sleep mode current
- New designs are requiring low current draw when disabled.
- Most bipolar competitors to the A4983 have 10 to 1000 times the current draw when disabled.