The A3930 and A3931 are 3-phase brushless DC (BLDC)Motor controllerfor N-channel external power MOSFETs. They integrate the various circuits needed to design cost-effective three-phase motor drive systems and are specifically designed for automotive applications.
The key requirement for automobiles is functionality that covers a wide range of input supplies. A unique charge-pump regulator provides appropriate (>10 V) gate drive when the battery voltage is as low as 7 V and allows the device to be used in a simplified oneGate drivers, can still operate with battery voltages as low as 5 V. Power dissipation in the charge pump is minimized by switching the voltage dual mode to dropout mode at a nominal operating voltage of 14 V when the supply voltage is low.
The bootstrap capacitor is used to provide the above battery supply voltage required for the N-channel MOSFET. The high-side drive internal charge pump allows DC (100% duty cycle) operation.
Internal fixed-frequency PWM current control circuitry can be used to regulate the maximum load current. The peak load current limit can be set by selecting the input reference voltage and an external sense resistor. The PWM frequency can be set by selecting an external RC timing network. To provide additional flexibility, a PWM input can be used to provide speed/torque control, allowing internal current control circuitry to set the maximum current limit.
Use synchronous rectification to improve efficiency. Integrated crossover control and programmable insensitive time protect the power FETs from breakdown. A single external resistor can be set for inductive time.
The only difference between the A3930 and A3931 is their response to an all-zero combination on the Hall input. In this case, the A3930 indicates a logic error, while the A3931 preemptively places the motor in an unstable starting position for use in a microprocessor-driven "sensorless" control system for the starting algorithm.
Both devices are available in a 48-pin LQFP package with exposed heat shield. This is small (81 mm2Power package, Pb-free, and 100% matte tin leadframe plating.
- High-current 3-phase gate driver for N-channel MOSFETs
- Synchronous rectification
- Cross-conduction protection
- Charge pump for 100% PWM and auto-end charge pump
- Integrated rectifier decoder logic
- Operates from a supply voltage range of 5.5 to 50 volts
- Comprehensive diagnostic output
- A +5 V Hall sensor power supply is available
- Low current sleep mode