Introduction
A4988 is a complete microstep motor driver with an internal converter, and is easy to operate. This product can operate 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. A4988 includes a fixed turn-off time current regulator, which can operate in slow or mixed decay modes. The converter is the key to the easy implementation of A4988. As long as a pulse is input in the "stepping" input, 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 very suitable for complex applications where microprocessors are unavailable or overloaded.
During the operation of the microstep, the pulse width modulation (PWM) 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 shutdown time, and then slowly decay during the remaining shutdown time. The mixed decay current control scheme can reduce audible motor noise, increase step accuracy and reduce power consumption. An internal synchronous rectification control circuit is provided to improve power consumption during pulse width modulation (PWM) operation. The internal circuit protection includes: overheating shutdown with lag, under-voltage lockout (UVLO), and cross-current protection. No special power-on sequence is required.
A4988 adopts a surface-mounted QFN package (ES), with a size of 5 mm × 5 mm and a nominal overall package height of 0.90 mm. It also features an exposed heat sink to enhance the heat dissipation function. This package is a lead-free package (suffix -T) and uses a 100-lead tin electroplated pin frame.
Functions and Benefits
Low RDS (on) output
Automatic current decay mode detection/selection
Mixed and slow current decay mode
Synchronous rectification for low power dissipation
Internal UVLO
Cross current protection
3.3 and 5 V compatible logic power supply
Overheat shutdown circuit
Ground short circuit protection
Load short circuit protection
Five selectable step modes: full, 1/2, 1/4, 1/8, and 1/16
Introduction
