48-V battery, HV brushless DC motor driver IC for EVs and HEVs

August 07, 2013 // By Graham Prophet
The A4900 from Allegro MicroSystems Europe is a high-voltage (600V) MOSFET gate-driver IC designed for driving brushless DC motors.

This device is designed for high-voltage motor control in hybrid and electric vehicles and 48V automotive battery systems such as electronic power steering, air-conditioning compressors, fans, pumps and blowers. The A4900 is also available in a non-automotive version for high-voltage industrial and commercial applications.

The new device incorporates six gate drives capable of driving a wide range of N-channel IGBT or power MOSFET switches. The gate drives are configured as three high-voltage high-side drives and three low-side drives. The high-side drives are isolated by up to 600V to allow operation with high bridge (motor) supply voltages, and use a bootstrap capacitor to provide a voltage higher than the supply gate drive voltage needed for N-channel FETs. Each FET can be controlled with a TTL logic level input compatible with 3.3V or 5V logic systems.

A single supply input provides the gate drive supply and the bootstrap capacitor charge source. An internal regulator from the single supply provides the lower internal voltage for the logic circuit. The A4900 provides internal monitors to ensure that the gate-source voltage of both the high-side and low-side external FETs is above 9V when active. The control inputs to the A4900 provide a very flexible solution for many motor control applications. Each driver can be driven with an independent PWM (pulse-width modulated) signal, allowing implementation of all motor excitation methods including trapezoidal and sinusoidal drive.

Integrated diagnostics provide indication of under-voltage, over-temperature and power bridge faults, and can be configured to protect the power switches under most short-circuit conditions. Detailed diagnostics are available in the form of a serial data word. The A4900KLQTR-T is supplied in a 44-lead QSOP (suffix ‘LQ’) package.

Allegro Microsystems; www.allegromicro.com/en/Products/Motor-Driver-And-Interface-ICs/Brushless-DC-Motor-Drivers/A4900.aspx