Allegro Unveils Automotive-grade MOSFET Pre-Driver ICs for Motor Control
Allegro Microsystems Inc. has introduced a range of automotive-grade MOSFET pre-driver ICs for in-vehicle motor control applications. The new devices, which will operate over a junction temperature range from -40 to +150°C, are designed for use in applications including wipers, blowers, water pumps, cooling systems, starter, electronic braking, steering, transmission and closure systems.
The range includes four devices: the A3935 3-phase power MOSFET controller; the A3940 full-bridge power MOSFET controller; the A3946 half-bridge power MOSFET controller; and the 3930/31 3-phase brushless dc controller and MOSFET driver. The A3935 is designed specifically for automotive applications that require high-power motors. Each device provides six high-current gate drive outputs capable of driving a wide range of n-channel power MOSFETs. The A3935 integrates a pulse-frequency modulated boost converter to create a constant supply voltage for driving the external MOSFETs. Direct control of each gate output is possible via six TTL-compatible inputs. A differential amplifier is integrated to allow accurate measurement of the current in the three-phase bridge.
The A3940 is also designed for applications that require high-power motors. Each device provides four high-current gate drive outputs capable of driving n-channel power MOSFETs in a full-bridge configuration. Bootstrap capacitors are used to provide the above battery supply voltage required for n-channel FETs. An internal charge pump for the high side allows for dc (100% duty cycle) operation of the bridge. Protection features include supply under / over-voltage, thermal shutdown, and motor lead short-to-battery and short-to-ground fault notification, plus a programmable dead-time adjustment for cross-conduction prevention.
The A3946 is designed for applications that require high-power unidirectional dc motors, three-phase brushless dc motors, or other inductive loads. It provides two high-current gate drive outputs: a high-side gate driver which switches an N-channel MOSFET to control current to the load, and a low-side gate driver that 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 charge pump for the high side allows for dc (100% duty cycle) operation of the half-bridge.
The A3930/31 is a 3-phase brushless dc motor controller for use with n-channel external power MOSFETs, and incorporates much of the circuitry required to design a cost-effective 3-phase motor drive system, including integrated commutation logic based on Hall sensor inputs. A charge pump regulator provides adequate gate drive for battery voltages down to 7V, and allows the device to operate with a reduced gate drive at battery voltages down to 5.5V. Power dissipation in the charge pump is minimised by switching from a voltage doubling mode at low supply voltage to a dropout mode at the nominal running voltage of 14V. The device features extensive diagnostic features and uses internal fixed-frequency PWM current control circuitry to regulate the maximum load current.
Packages include SSOP, TSSOP, SOIC and the ultra-compact LQPF-48. All are available in lead (Pb) free versions.
