The A4984 is a complete oneMicrostepping motor driver, with a built-in converter for easy operation. The driver operates bipolar stepper motors in full, 1/2, 1/4, and 1/8 step modes. Step mode can be selected via MSx logic input. It has drive capabilities up to 35 V and ±2 A. The A4984 includes a fixed downtimeCurrent regulator, the regulator can operate in slow or mixed attenuation mode.
The ET package adds no connection pins between key output, sense, and power pins to meet customer requirements for smoke-free no fire (NSNF) designs. Therefore, even if a short circuit occurs between the pin and the adjacent pin, the device will not smoke or catch fire. In addition, the device will not smoke or catch fire even if any of the pins are shorted or open to ground.
The converter is key to the A4984'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 A4984 interface is ideal for complex applications where microprocessors are unavailable or overloaded.
In microstepping operation, the chopper control within the A4984 automatically selects the current attenuation 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 A4984 is available in three surface mount packages: two QFN packages: 4 mm × 4 mm, 0.75 mm nominal overall height ES and 5 mm × 5 mm × 0.90 mm ET. The LP package is a 24-pin TSSOP. All three packages have exposed pads for improved heat dissipation, are Pb-free (suffix: –T), and feature 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
Ultra-thin QFN and TSSOP packages
Thermal shutdown circuit
Short-to-ground protection
Load short-circuit protection
Low current sleep mode, Smokeless, Smokeless, Fireless (NSNF) specification (ET package) compliant