ALLEGRO A3930KJPTR-T

The A3930 and A3931 are three-phase brushless DC (BLDC) motor controllers for use with N-channel external power MOSFETs. They incorporate much of the circuitry required to design a cost-effective three-phase motor drive system, and have been specifically designed for automotive applications. A key automotive requirement is functionality over a wide input supply range. A unique charge pump regulator provides adequate (>10 V) gate drive for battery voltages down to 7 V, and allows the device to operate with a reduced gate drive at battery voltages down to 5.5 V. Power dissipation in the charge pump is minimized by switching from a voltage doubling mode at low supply voltage to a dropout mode at the nominal running voltage of 14 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 for 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 is set by the selection of an input reference voltage and external sensing resistor. The PWM frequency is set by a user-selected external RC timing network. For added flexibility, the PWM input can be used to provide speed and torque control, allowing the internal current control circuit to set the maximum current limit. Efficiency is enhanced by using synchronous rectification. The power FETs are protected from shoot-through by integrated crossover control with dead time. The dead time can be set by a single external resistor. The A3930 and A3931 only differ in their response to the all-zero combination on the Hall inputs. In this state, the A3930 indicates a logic fault, but the A3931 pre-positions the motor in an unstable starting position suitable for start-up algorithms in microprocessor-driven “sensor-less” control systems. Both devices are supplied in a 48-pin LQFP with exposed thermal pad. This is a small footprint (81 mm²) power package. The package is lead (Pb) free, with 100% matte-tin leadframe plating. The A3930 and A3931 devices provide commutation and current control for three-phase brushless DC (BLDC) motors with integrated Hall-effect (HE) sensors. The motor current is provided by an external three-phase N-channel MOSFET bridge which is controlled by the A3930/A3931, using fixed-frequency pulse width modulation (PWM). The use of PWM with N-channel MOSFETs provides the most cost-effective solution for a high-efficiency motor drive. The A3930/A3931 provides all the necessary circuits to ensure that the gate-source voltage of both high-side and low-side external MOSFETs are above 10 V, at supply voltages down to 7 V. For extreme battery voltage drop conditions, functional operation is guaranteed down to 5.5 V but with a reduced gate drive. The A3930/A3931 also decodes the commutation sequence from three HE sensors spaced at 120° in the electrical cycle, and ensure no cross-conduction (shoot through) in the external bridge. Individual pins provide direction, brake, and coast control. Motor current can be sensed by a low-value sense resistor, RSENSE, in the ground connection to the bridge, amplified and compared to a reference value. The A3930/A3931 then limits the bridge current on a cycle.

• High current three-phase gate drive for N-channel MOSFETs
• Synchronous rectification
• Cross-conduction protection
• Charge pump and top-off charge pump for 100% PWM
• Integrated commutation decoder logic
• Operation over 5.5 to 50 V supply voltage range
• Extensive diagnostics output
• Provides +5 V Hall sensor power
• Low-current sleep mode