The A3985 is a flexibleDual full-bridge gate driversIt is suitable for driving a variety of high-power industrial bipolar 2-phase stepper motors or 2-phase brushless DC motors. It can also be used to drive two independent torque motors or solenoid drives. Motor power is provided by an external N-channel power MOSFET with a supply voltage of 12 to 50 volts.
Two serial registers provide full digital control for programming shutdown time, blanking time, downtime, mixed attenuation factor, synchronous rectification, master clock source selection, scale ratio, and no-load mode. All internal time can be taken from the master clock, which can be generated by the chip or provided by an external clock such as the clock of the host controller. Programmable splitters support a wide range of external system clock frequencies.
The built-in fixed-off-time PWM current-controlled timer can be programmed through a serial interface, allowing operation in low-speed, fast, and fixed current-decay modes. The desired load current level and direction can be set through the serial port with one direction bit and two 6-bit linear DACs and the reference voltage. The 7-bit controller enables flexible torque control to support different step modes, from microstep to full-step drive. The load current within the external power MOSFET full bridge is set to 1.56% increments of the maximum value.
The bootstrap capacitors provide the supply voltage required for the high-end N-channel MOSFETs described above. Synchronous rectification is improved by applying synchronous rectification, and integrated crossover control and programmable downtime save power FETs from breakdown.
In addition, crossover current control and internal circuit protection provide overtemperature power-off (with hysteresis) and undervoltage lockout protection. No special power-on sequencing is required. The component is available in a 38-pin TSSOP package (package LD) with 100% matte tin leadframe plating.
- The serial interface is suitable for all-digital control
- N-channel MOSFET dual full-bridge gate drivers
- Dual 6-bit DAC currents are given
- Operates from a supply voltage range of 12 to 50 volts
- Synchronous rectification
- Cross-conduction protection
- Adjustable mixing attenuation
- Fixed downtime PWM current control
- Low current no-load mode