HMI Introduces a Single-Channel High-Side Switch Ideal for Automotive Applications

HMI HL8518
Written by Kirsten Campbell

HMI, a leading provider of advanced analog and power management technologies announced the launch of its HL8518, a single-chip 80 mΩ high-side switch ideal for automotive applications needing power switch for low wattage lamp, high-side relays and valves, and general resistive, inductive, and capacitive loads.

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 utilizes 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.

According to David Nam, CEO of HMI, “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, categorizing devices based on the number of successful test cycles, and highlights the HL8518’s exceptional achievement, securing Class-A certification by enduring an impressive 1 million short circuits to ground.”


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Kirsten Campbell is a Marketing Tornado and junk robot of information. Analytical and creative, she has been in marketing and communications since 2008 and worked with everyone from small businesses to your favorite household names. 


Ask her about the time she made a numismatics blog interesting (yes, really) or wrote an obit for a family she never met.


An ardent admirer of corporate snark played out online, Kirsten loves Reese’s peanut butter cups and still isn't over the Mars Rover.

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HMI Introduces a Single-Channel High-Side Switch Ideal for Automo…

by Kirsten Campbell time to read: 1 min