Description
The A4988 is a complete microstep motor driver with an integrated converter, which is easy to operate. This product can operate bipolar stepping motors in full, half, 1/4, 1/8 and 1/16 step modes, with an output drive performance of up to 35 V and ±2 A. The A4988 includes a fixed off-time current regulator that can operate in slow or mixed decay modes.
The converter is the key to the easy implementation of the A4988. Just input a pulse in the "step" input, and the motor can be driven 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 applications where complex microprocessors are unavailable or overloaded.
During microstep operation, the chopper control within the A4988 can automatically select the current decay mode (slow or mixed). In the mixed decay mode, the device is initially set to rapidly decay during a portion of the fixed off-time, and then decay slowly during the remaining off-time. The mixed decay current control scheme can reduce audible motor noise, increase step accuracy, and reduce power consumption.
It provides an internal synchronous rectification control circuit to improve power consumption during pulse width modulation (PWM) operation. Internal circuit protection includes: thermal shutdown with hysteresis, under-voltage lockout (UVLO), and cross-current protection. No special power-on sequencing is required.
The A4988 uses a surface mount QFN package (ET) with dimensions of 5 mm × 5 mm and a nominal overall package height of 0.90 mm. It features an exposed heat sink pad to enhance heat dissipation. This package is lead-free (suffix -T) and has a 100% matte tin-plated lead frame.
Features
• Low RDS(on) output
• Automatic current decay mode detection/selection
• Hybrid and slow current decay modes
• Synchronous rectification for low power dissipation
• Internal UVLO
• Cross-current protection
• 3.3 and 5 V compatible logic supply
• Over-temperature shutdown circuit
• Ground short-circuit protection
• Load short-circuit protection
• Five selectable step modes: full, 1/2, 1/4, 1/8 and 1/16