Automotive gate driver provides more flexibility for motor control

Automotive gate driver provides more flexibility for motor control

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By Christoph Hammerschmidt

The L9908 integrated three-phase gate driver unit (GDU) from STMicroelectronics is designed for automotive applications. The device can be used in systems with operating voltages of 12, 24 or 48 V and has flexible input and output channels, so it can be applied in a wide range of applications in vehicles with conventional drive or with hybrid/electric drive.

Dedicated source connections for the high- and low-side FETs (field-effect transistors) of each half-bridge allow independent, user configuration of the output channels to drive different loads. In addition, six separate PWM input terminals are provided, allowing individual management of the pre-driver stages to implement different motor control strategies.

To ensure high accuracy, three differential current monitors for ground-related measurements and three channels for real-time monitoring of phase voltages are provided. The equipment is complemented by a rich selection of diagnostic and protection functions.

The L9908’s combination of high integration, flexibility and accuracy simplifies design, saves space and improves control of liquid pumps, pumps and fans in ventilation and cooling systems and electronic seat actuators. It is also suitable for use in traction inverters for mild hybrid internal combustion engine vehicles and all-electric 48 V city cars.

The integrated diagnostic functions allow the L9908 to be used in safety-related systems such as Autonomous Emergency Braking (AEB) and Advanced Electronic Power Steering (EPS), facilitating ISO 26262 certification.

Included safety features include SPI-programmable dead-time insertion with shoot-through diagnostics and protection, open-load detection, and diagnostics for shorts to ground and battery. There is also an SPI-programmable temperature warning and an SPI-readable junction temperature measurement function. Other diagnostic features include detection of an interrupted ground connection, detection of over- and undervoltages at the power supply terminals and at the FET driver supply, monitoring of the system clock, an SPI window watchdog and an error status flag.

The ability to use the L9908 in single (12 V), dual (24 V) and 48 V battery applications results from the device’s wide motor supply voltage range, from 4.5 V to 75 V, with voltages between -14 V and +95 V tolerated at the motor terminals. The chip’s internal logic is powered by an internally generated voltage of 3.3 V, and the digital I/O lines are compatible with 3.3 V and 5 V.

The AEC-Q100 qualified L9908 has a thermally optimised TQFP48 package and is available for immediate shipment.

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