The unique ST L99MH98 8-channel gate driver reduces power dissipation and the bill of materials by enabling the building of automotive motor drives without sensing resistors.
In addition to single high-side/low-side powering mechanisms like seat-position adjusters, window lifters, sunroofs, pumps, seatbelt pretensioners, and other actuators, the L99MH98 can power four external full bridges and eight half bridges.
A charge pump with an output that can regulate a reverse-battery protection MOSFET is part of the internal circuitry of the L99MH98 8-channel gate driver, which may also drive resistive loads like heaters.
The drivers can control both logic-level and standard-level MOSFETs, but they can also drive a lot of external MOSFETs thanks to their expanded gate current capabilities, which can be programmed up to 120mA.
In order to reduce electromagnetic emissions, three-stage gate control applies the gate signal in three steps.
Designed to Provide Each MOSFET’s Drain-Source Voltage (VDS) to an Analog-Digital Converter (ADC), the L99MH98 Leverages:
- Indirect current measurement to replace sensing resistors.
- This ST-patented technique calculates the drain current in each MOSFET by combining the measured VDS with RDS(on)predicted using sensed temperature.
- The system is calibrated at manufacture to find the nominal RDS(on)values, enabling predictions to be made using the MOSFETs’ resistance-versus-temperature curves.
The programmable multi-failsafe function, which is another innovation that is also ST-patented, improves reliability by shutting down particular bridges to guard against defects while preserving the functionality of unaffected bridges.
Depending on the kind of problem, multi-failsafe selectively disables diagnostics, watchdog, and charge pump operations. It also detects failures such as supply overvoltage, high-side over/undervoltage, thermal warning, charge-pump failure, and VDS-monitoring failure.
The L99MH98 satisfies ISO 26262 requirements for functional-safety applications up to safety integrity level (ASIL) B and is AEC Q100 qualified.
Availability, Packaging and Pricing
Available now in a VFQFN48L package with wettable flanks and exposed underside cooling pad, the L99MH98 8-channel gate driver is priced from $2.44 for orders of 1000 pieces.