The A3981 and A4980 stepper-motor driver ICs from Allegro Microsystems Europe can operate bipolar stepper motors in full-, half-, quarter- and 16th-step modes at up to 28V and ±750mA in automotive, consumer and industrial applications. The driver ICs offer a single-chip solution with internal digital timing circuitry and a built-in translator for operational purposes. The A3981 driver IC can be controlled by step and direction inputs, or through a serial port that can be used to program integrated features. The A4980 driver IC is identical except for a low-voltage operation feature which allows it to run down to a load supply voltage of 3.3V. The low- voltage operation may be necessary in some automotive applications where the battery voltage during cold cranking can drop to low levels. The built-in current regulator can operate in fixed off-time or fixed-frequency pulse-width modulation modes. The phase current tables can be programmed through the serial peripheral interface to create microstepping current profiles to improve the motor performance for specific applications. The current in each phase of the motor is controlled through a double-diffused metal-oxide semiconductor full bridge.
