The A4988 is a complete Microstepping motor driver, with a built-in converter for easy operation. It operates bipolar stepper motors in full, half, 1/4, 1/8 and 1/16 step modes with output drive performance up to 35 V and ±2 A. The A4988 includes a fixed off-timeCurrent regulation, which can operate in slow or mixed attenuation mode.
The converter is key to the A4988's ease of implementation. Simply enter a pulse into the "step" input to drive the motor to generate microsteps. There is no need for phase sequence tables, high-frequency control lines, or complex interface programming. The A4988 interface is ideal for complex applications where microprocessors are unavailable or overloaded.
In microstepping operation, the chopping control within the A4988 automatically selects the current decay mode (slow or mixed). In mixed attenuation mode, the device is initially set to decay rapidly during part of the fixed downtime and then slow decay during the remaining downtime. Hybrid attenuation current control schemes reduce audible motor noise, increase step accuracy, and reduce power consumption.
Internal synchronous rectification control circuitry is provided to improve power consumption during pulse-width modulation (PWM) operation. Internal circuit protection includes thermal shutdown with hysteresis, undervoltage lockout (UVLO), and crossover current protection. No special power-on sequencing is required.
The A4988 is available in a surface-mount QFN package (ES) measuring 5 mm × 5 mm, with a nominal overall package height of 0.90 mm, and an exposed heatsink for enhanced cooling. The package is lead (suffix –T) and features 100% matte tin leadframe plating.
- Low RDS (On)output
- Automatic current decay mode detection/selection
- Mixed with slow current attenuation modes
- Synchronous rectification for low power dissipation
- Internal UVLO
- Crossover current protection
- 3.3 and 5 V compatible logic supplies
- Thermal shutdown circuit
- Short-to-ground protection
- Load short-circuit protection
- Five selectable step modes: full, 1/2, 1/4, 1/8 and 1/16