Automotive 3-Phase MOSFET Driver


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The A4935 is a 3-phase controller for use with N-channel external power MOSFETs and is specifically designed for automotive applications.

A unique charge pump regulator provides full (>10 V) gate drive for battery voltages down to 7 V and allows the A4935 to operate with a reduced gate drive, down to 5.5 V.

A bootstrap capacitor is used to provide the above-battery supply voltage required for N-channel MOSFETs. An internal charge pump for the high-side drive allows DC (100% duty cycle) operation.

Full control over all six power FETs in the 3-phase bridge is provided, allowing motors to be driven with block commutation or sinusoidal excitation. The power FETs are protected from shoot-through by integrated crossover control and resistor-adjustable dead time.

Bridge current can be measured using an integrated current sense amplifier. This is an uncommitted differential amplifier with a below-ground common mode range allowing it to be used in low-side current sense applications. Gain and offset are defined by external resistors.

Integrated diagnostics provide indication of undervoltage, overtemperature, and power bridge faults. They can be configured to protect the power FETs under most short circuit conditions. Detailed diagnostics are available as a serial data word.

Allegro recommended automotive-qualified Hall latches: APS122x5 and APS122x0

  • High current 3-phase gate drive for N-channel MOSFETs
  • Cross-conduction protection with adjustable dead time
  • Top-off charge pump for 100% PWM
  • Charge pump for low supply voltage operation
  • Uncommitted current sense amplifier
  • 5.5 to 50 V supply voltage range
  • Compatible with 3.3 V and 5 V logic
  • Extensive diagnostic outputs
  • Low-current sleep mode

The A4935 is supplied in a 48-pin LQFP with exposed thermal pad, (suffix JP). This is a small footprint (81 mm2) power package. It is lead (Pb) free with 100% matte tin leadframe plating.



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Reverse Battery Protection Scheme for Automotive Applications