The A3968 controls two DC motors bidirectionally. The device includes two full bridges capable of continuously outputting ±650 mA and operating voltages up to 30 volts. Internally fixed frequency, pulse width modulation (PWM) and Current control circuitControl the motor winding current. 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. Capacitors in the RC timing network can also identify a user-selectable 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.Energized driverHas Allegro®Patented Satlington®Output structure. Satlington outputs combine the low voltage drop of saturated transistors with Darlington's high peak current capability.
For each bridge, the Input A and Input B ports determine the load current polarity by initiating the appropriate power and sink driver pairings. When logic low is applied in the bridge "input", the braking function is enabled. In braking mode, the two power drives are turned off and the two sink drivers are on, thus dynamically braking the electric motor. When a logic high is applied in the two "inputs" of the bridge, all output drivers are disabled.
No special power-on sequencing is required. Internal current protection includes thermal shutdown with delay, ground-clamped flyback diodes, and crossover current protection.
The A3968 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 Pb-free and features 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
- Braking mode
- A blank window that the user can select
- Internal ground clamp and flyback diode
- Internal thermal shutdown circuitry
- Crossover current protection and UVLO protection