The A5985 is a complete microstepping motor driver with built-in translator for easy operation. It is designed to operate bipolar stepper motors from full-step up to 1/32 step modes. Step modes are selectable by MSx logic inputs. It has an output drive capacity of up to 40 V and ±2 A.
A5985 introduces a proprietary Adaptive Percent Fast Decay (APFD) algorithm to optimize the current waveform over a wide range of stepper speeds and stepper motor characteristics. APFD adjusts on-the-fly the amount of fast decay during a PWM cycle to keep current ripple at a low level over the various operating conditions. This adaptive feature improves performance of the system resulting in reduced audible motor noise, reduced vibration, and increased step accuracy.
The translator is the key to the easy implementation of the A5985. 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 A5985 interface is an ideal fit for applications where a complex microprocessor is unavailable or is overburdened.
Internal 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.
The A5985 is supplied in a surface-mount QFN package (ET), 5 mm × 5 mm, with a nominal overall package height of 0.90 mm and an exposed pad for enhanced thermal dissipation. It is lead (Pb) free (suffix –T), with 100% matte tin-plated leadframes.