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ST's L99H92 automotive gate driver provides the SPI port required for current setting and diagnostic functions, as well as charge pumping and safety protection, with the addition of two new current-sense amplifiers for monitoring system operation.

The L99H92 consists of two high-side and two low-side drivers that can control a full-bridge to drive a single bi-directional DC motor or two half-bridges to drive two uni-directional motors. This highly integrated and easy-to-configure driver is suitable for use in a variety of automotive systems, including power sunroofs, window lifts, power boots, power sliding doors and seat belt pretensioners.

A charge pump powers the high-side driver, ensuring that the driver operates correctly when the vehicle battery voltage fluctuates, and that the charge pump still outputs properly when the voltage is as low as 5.41V. There is a charge pump output on an external pin that can be used to control the MOSFET switching tubes of the battery mounted reverse protection circuit.

The gate drive current can be set via the SPI port to control the slew rate and minimise electromagnetic emissions and power dissipation. While external components are often used to set the slew rate of conventional drivers, the new driver's current setting function allows up to four external discrete components per MOSFET to be saved. 170mA maximum drive current gives designers the flexibility to use the driver with a wide range of external MOSFET switching tubes, including high-power devices with large gate capacitance.

The L99H92 was designed to improve reliability and safety by providing comprehensive system protection and diagnostic features for applications. The overcurrent protection feature allows you to set a current threshold to detect overcurrent by monitoring the MOSFET drain current. In addition, the high and low side cross conduction protection function can set the dead time to ensure the safety and energy efficiency of the bridge. Other protection features include over-temperature warning shutdown, analogue-digital power input over-voltage and under-voltage protection, as well as diagnostic off-state mode open load and output short-circuit detection.

Fail-safe inputs immediately shut down all MOSFET power tubes, and dedicated diagnostic pins provide emergency fault warnings without having to wait for SPI periodic transmission signals.

In addition, the new driver incorporates two current-sense amplifiers for system condition monitoring, helping to minimise bill-of-material costs. These amplifiers are suitable for detecting current in high-side, low-side and inline circuits, with individually settable gains, low offset voltage and low temperature drift. The current-sense amplifiers can be individually switched off to reduce current consumption at idle.