Single-channel high-side switch is ideal for automotive applications

HMI has launched its HL8518, a single-chip 80mOhm high-side switch ideal for automotive applications requiring power switches for low-wattage lamps, high-side relays and valves, and general resistive, inductive, and capacitive loads.

The device is a single-channel, high-side power switch with an 80mOhm (typical) Rds(on) power FET. It incorporates comprehensive diagnostic capabilities, full protection mechanisms, and a high-precision current detection function. Intelligent load control also improves system safety.

Available in two types, Version A outputs the digital diagnosis from the FLTn pin employing an open drain structure. During a fault condition, this pin is pulled down to GND. An external pullup resistor connecting to a 3.3V or 5V power rail is needed to match the microcontroller I/O voltage level. For version B, the device outputs a current from the ISNS pin, a 1/K ratio of the load current. The ISNS pin can also report a fault by pulling up the voltage of VISNS_H. When the DIAG pin is pulled low, the FLTn/ISNS pin is set to a high impedance state.

The device uses an internal power FET with adjustable current limits through an external resistor connection, and an internal charge pump facilitates efficient gate control. The device actively regulates output current, and connecting the ILIM pin to the ground establishes a default current limit. However, increased power consumption may trigger thermal shutdown, disconnecting the power path and decreasing device temperature. Upon cooling, the power FET is reactivated, restoring the power path.

David Nam, CEO of HMI, said: "In automotive scenarios, the reliability of the high-side power switch device is crucial, particularly in short-circuit conditions."

The AEC – Q100-012 outlines testing standards for sustained short-circuit performance, categorising devices based on the number of successful test cycles. It highlights the the device's outstanding achievement of securing Class-A certification by enduring an impressive one million short circuits to ground.