Compact DMOS microstepping motor driver IC with built-in translator

The high output drive capacity is significantly high than that of most competitive devices, and provides an additional safety margin for high reliability designs. The use of synchronous rectification reduces power dissipation and minimises the need for expensive Schottky diodes, while the low-resistance DMOS outputs further limit power dissipation and allow higher average output currents because of the lower die temperature rise.



The built-in translator circuitry makes the A4983 very easy to operate, and requires only two control lines compared with eight or more for competing devices. Simply inputting one pulse on the 'step' input drives the motor by one microstep. There are no phase sequence tables, high-frequency control lines, or complex interfaces to program, making the device an ideal fit for applications where a complex microprocessor is unavailable or overburdened.



The A4983 includes a fixed off-time current regulator, which has the ability to operate in slow or mixed decay modes. 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.



Internal circuit protection includes thermal shutdown with hysteresis, undervoltage lockout (UVLO), and crossover-current protection. Special power-on sequencing is not required. A 'sleep' mode with a current consumption of only 10 µA is also available.



The A4983 is supplied in a 28-lead 5.0 mm x 5.0 mm x 0.9 mm QFN package with exposed thermal pad (suffix ET). The package is lead (Pb) free (suffix -T), with 100% matt tin plated leadframe.