Features
- 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
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 component 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 commutation logic for Hall sensor ICs configured for 120-degree spacing. The Hall 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 shutdown.
The LD package is lead (Pb) free, with 100% matte tin plated leadframe.
Functional Block Diagram
