A3938 Datasheet | Allegro MicroSystems

FEATURES AND BENEFITS - Drives a wide range of N-channel MOSFETs - Low-side synchronous rectification - Power MOSFET protection - Adjustable dead time for cross-conduction protection - Selectable coast or dynamic brake on power-down or RESET input - Fast/slow current decay modes - Internal PWM current control - Motor lead short-to-ground protection - Internal 5 V regulator - Fault diagnostic output - Thermal shutdown - Undervoltage protection Package 38-pin TSSOP (suffix LD): Not to scale DESCRIPTION The A3938 is a three-phase, brushless DC motor controller. It has a high-current gate drive capability that allows driving of a wide range of power MOSFETs and can support motor supply voltages to 50 V. The A3938 integrates a bootstrapped high-side driver to minimize the external ponent count required to drive N-channel MOSFET drivers. Internal fixed off-time, PWM current-control circuitry can be used to regulate the maximum load current to a desired value. The peak load current limit is set by the user’s selection of an input reference voltage and external sensing resistor. A userselected external RC timing network sets the fixed off-time pulse duration. For added flexibility, the PWM input can provide speed/torque control where the internal current control circuit sets a limit on the maximum current. The A3938 includes a synchronous rectification feature . This shorts out the current path through the power MOSFET reverse body diodes during PWM off-cycle current decay. This can minimize power dissipation in the MOSFETs, eliminate the need for external power clamp diodes, and potentially allow a more economical choice for the MOSFET drivers. The A3938 provides mutation logic for Hall sensors configured for 120-degree spacing. The H-all input pins are pulled-up to an internally-generated 5 V reference. Power MOSFET protection features include: bootstrap capacitor charging current monitor, regulator undervoltage monitor, motor lead short-to-ground, and thermal...