STMicroelectronics Car gauge DC motor predriver simplifies EMI optimization design, saving energy and reducing consumption

     STMicroelectronics' L99H92 gauge gate driver provides the SPI port required for current setting and diagnostic functions, as well as charge pump and safety protection, and two additional current detection amplifiers for monitoring system health.

     The L99H92 contains two high-side drivers and two low-side drivers, which can control a full bridge to drive a bi-directional DC motor, and can control two half-bridges to drive two unidirectional motors. This highly integrated and easy-to-configure drive is suitable for a variety of automotive systems, including a power sunroof, window lift, power trunk, power sliding doors and seat belt pretensioner.

     The charge pump supplies power to the high-side driver, ensuring that the driver is operating properly when the vehicle battery voltage fluctuates, and the charge pump can still output normally when the voltage is low to 5.41V. There is a charge pump output on an external pin that can be used to control the MOSFET switch tube with a battery-mounted reverse protection circuit.

     The gate drive current can be set through the SPI port to control the voltage swing rate and minimize electromagnetic radiation and dissipated power. While external components are often used to set the voltage swing rate of traditional drivers, the current setting feature of the new driver can save up to four external discrete components per MOSFET. The maximum drive current of 170mA gives designers the flexibility to use drivers with a variety of external MOSFET switching tubes, including high-power devices with large gate capacitors.

     The L99H92 is designed to improve reliability and safety, providing comprehensive system protection and diagnostic capabilities for applications. The overcurrent protection function allows you to set a current threshold and 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. Additional protection features include overheat warning shutdown, analog and digital power input overvoltage and undervoltage protection, and off-state diagnostic mode open load and output short circuit detection.

     Fail-safe inputs shut down all MOSFET power tubes immediately, and dedicated diagnostic pins provide emergency fault warnings without waiting for the SPI to transmit signals regularly.

     In addition, the new driver integrates two current detection amplifiers for system condition monitoring, helping to minimize material costs. These amplifiers are suitable for detecting currents in high side, low side and inline circuits, the gain can be set individually, and have low offset voltage and low temperature drift characteristics. The current detection amplifier can be turned off individually to reduce current consumption when idle.