HMI introduces High-Side Switch for automotive applications

HMI has launched the HL8518, a single-chip 80 mΩ high-side switch intended for automotive applications needing power switch for low wattage lamp, high-side relays and valves, and general resistive, inductive, and capacitive loads.

Credit: HMI

The HL8518 is a single-channel, high-side power switch with 80 mΩ (typical) Rds(on) power FET. It combines comprehensive diagnostic capabilities, full protection mechanisms, and a high-precision current detection function. Through intelligent control of the load, it also enhances 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 3.3 V or 5 V power rail is required to match the microcontroller I/O voltage level.

For Version B, the device outputs a current from the ISNS pin which is 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 HL8518 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 reducing device temperature. Upon cooling, the power FET is reactivated, restoring the power path.