The A3966 drives two windings of a two-phase bipolar stepper motor. The device includes two full bridges capable of a continuous output current of ±650 mA and operating voltages up to 30 V. The motor winding current can be controlled by internal fixed frequency, pulse width modulation (PWM), and current control circuitry. The peak load current limit can be set by the user by selecting the reference voltage and current sense resistor.
The user can set the fixed frequency pulse duration by selecting an external RC timing network. RC timing networkcapacitorIt can also be determined that the user selects a blank window that prevents false triggering of the PWM current control circuit during switching transitions.
To reduce chip power dissipation, the full-bridge power output has been optimized to accommodate low saturation voltages. The sink driver features Allegro's® patented Satlington® output structure. Satlington outputs combine the low voltage drop of saturated transistors with Darlington's high peak current capability.
The "phase" input of each bridge controls the polarity of the load current by selecting the appropriate source and sink-in driver. When the Enable input for each bridge is high, the output driver is disabled. No special power-on sequencing is required. Internal circuit protection includes thermal shutdown due to hysteresis, ground-clamped flyback diodes, and crossover current protection.
The A3966 is available in a 16-pin plastic SOIC package with two pins connected to the lower pad via an internal fuse for enhanced heat dissipation. These pins are at ground potential and do not require electrical isolation. The device is lead (Pb) free and has 100% matte tin leadframe plating.
- ± 650 mA continuous output current
- 30 volt output voltage rating
- Internal fixed frequency PWM current control
- Satlington® sink current driver
- The user can select a blank window
- Internal ground clamp and flyback diode
- Internal thermal shutdown circuitry
- Crossover current and undervoltage lockout (UVLO) protection