The A4983 is a DMOS microstepping motor driver with a 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 35V and ±2 A. The A4983 includes a fixed off-time current regulator, which can operate in slow or mixed decay modes. This motor driver is targeted toward the office automation, industrial, and medical markets.
The translator is the key to the easy implementation of the A4983. 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 A4983 interface is ideal 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 circuit protection includes thermal shutdown with hysteresis, undervoltage lockout (UVLO), and crossover-current protection. Special power-on sequencing is not required. Allegro’s A4983 is supplied in a 5 x 5 x 0.9 mm QFN package with an exposed thermal pad (suffix ET). The package is lead-free, with a 100% matte tin-plated leadframe.
- Low RDS(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 5V compatible logic supply
- Very thin profile QFN package
- Thermal shutdown circuitry
