Half-Bridge Power MOSFET Controller


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The A3946 is designed specifically for applications that require high power unidirectional DC motors, three-phase brushless DC motors, or other inductive loads. The A3946 provides two high-current gate drive outputs that are capable of driving a wide range of power N-channel MOSFETs. The high-side gate driver switches an N-channel MOSFET that controls current to the load, while the low-side gate driver switches an N-channel MOSFET as a synchronous rectifier.

A bootstrap capacitor provides the above-battery supply voltage required for N-channel MOSFETs. An internal top-off charge pump for the high side allows DC (100% duty cycle) operation of the half-bridge.

Allegro recommended automotive qualified hall latches: APS122x5 and APS122x0


  • On-chip charge pump for 7 V minimum input supply voltage
  • High-current gate drive for driving a wide range of N-channel MOSFETs
  • Bootstrapped gate drive with charge pump for 100% duty cycle
  • Overtemperature protection
  • Undervoltage protection
  • -40°C to 135°C ambient operation

16-pin TSSOP with exposed thermal pad (Suffix LP)


Part Number Specifications and Availability