AUTOMOTIVE INDUSTRY STMicroelectronics’ automotive gate driver boosts motor-control flexibility
STMicroelectronics’ L9908 integrated automotive three-phase gate driver unit (GDU) operates in 12V, 24V, or 48V systems and has flexible input and output channels to fulfil numerous applications in conventional and hybrid/electric vehicles.
Dedicated source connections to the high-side and low-side FETs (field-effect transistors) of each half bridge let users configure the output channels independently to drive various types of loads. In addition, six separate PWM (pulse-width modulation) input pins allow independent management of the pre-driver stages for different motor-control strategies.
High accuracy is assured, with three differential current monitors for ground-referenced measurements and three channels for real-time phase-voltage monitoring. There is also a rich set of diagnostic and protection features.
By combining high integration, flexibility, and accuracy, the L9908 simplifies design, saves space, and enhances control of low-voltage fluid pumps, pumps and blowers in ventilation and cooling systems, and electronic seat controls. It can be also used in traction inverters for mild-hybrid internal combustion engine (ICE) vehicles and 48V full-electric city cars.
Moreover, the L9908’s built-in diagnostics allow use in safety-related systems such as autonomous emergency braking (AEB) and advanced electronic power steering (EPS), simplifying certification according to ISO 26262.
The safety features include SPI-programmable dead-time insertion with shoot-through diagnostic and protection, open-load detection, and short-to-ground and short-to-battery diagnostics. There is also an SPI-programmable temperature warning and SPI-readable junction-temperature measurement. Other diagnostics include ground-loss detection, over-voltage and under-voltage detection on the power supply pins and FET-driver supply, system-clock monitoring, SPI window watchdog, and a fault-status flag.
The flexibility to use the L9908 gate driver in single (12V), dual (24V), and 48V battery applications comes from its wide motor supply-voltage range, from 4.5V to 75V, with the ability to tolerate -14V to 95V on motor-connection pins. The on-chip logic is supplied from an internally generated 3.3V supply and digital I/Os are 3.3V- and 5V-compatible.