STMicroelectronics reveals integrated hot-swap and ideal-diode controller

The ideal-diode controller drives an external MOSFET replacing a Schottky diode conventionally used for reverse-input protection and output-voltage holdup. The reduced voltage drop across the MOSFET reduces power dissipation during normal operation, compared to the forward voltage of the Schottky diode. When a reverse-voltage event occurs, in case of faults like power source failure, brownout or input short-circuit, turning off the MOSFET blocks the associated reverse-current transients.

The ideal-diode controller circuit also provides power ORing, to switch between a main and backup battery to ensure uninterrupted supply to safety-critical equipment such as autonomous driving and advanced driver assistance systems (ADAS).

The integrated hot-swap controller drives a second external N-channel MOSFET to protect loads during hot-swap events. A soft-start function controls the turn-on transient of this second MOSFET by charging a capacitor of known value connected to its gate at constant current to avoid high inrush currents. The overvoltage and undervoltage pins cut off the output voltage whenever the input voltage is not within specified thresholds.

The STPM801 also includes protection features and monitoring suitable for applications that meet functional safety requirements for systems up to Automotive Safety Integrity Level (ASIL) D according to ISO 26262. The features are packaged within a 5 x 5mm VFQFN-32 footprint, saving PCB space, and minimizing demand for external components.

Operating from a 4V-65V supply voltage, and with 25µA quiescent current, the STPM801 withstands automotive electrical hazards and minimizes battery drain when the vehicle is turned off. It is used in zonal/body ECUs, ADAS ECUs, high-performance computing ECUs, infotainment ECUs, redundant power delivery systems, and dual-battery systems.

The STPM801 is in mass production now and available from $3.00 for orders of 1,000 pieces.