Italian Semiconductor Launches an Ideal Diode Controller for Thermal Switching, Suitable for ASIL-D Automotive Safety Critical Applications

    This ideal diode controller drives an external MOSFET switch, replacing the Schottky diodes commonly used in input reverse protection and output voltage retention circuits in the past. The voltage drop on MOSFETs is lower than the forward voltage of Schottky diodes, therefore, the dissipated power during normal operation is also lower than that of diodes. When faults such as power failure, power outage, or input short circuit cause reverse voltage events, turning off the MOSFET power transistor can prevent related reverse current transient events.

    This ideal diode control circuit also provides an ORing controller for switching between the main power supply and the backup battery, ensuring uninterrupted power supply for safety critical equipment such as autonomous driving and advanced driving assistance systems (ADAS).

    The built-in hot switching controller drives the second external N-channel MOSFET transistor to protect the load during the switching between the main power supply and backup battery. The soft start function charges a capacitor with a known capacitance value connected to the gate with a constant current to control the conduction transient event of the second MOSFET transistor and avoid the occurrence of high surge currents. As long as the input voltage is not within the specified threshold, the overvoltage and undervoltage pins will cut off the output voltage.

    STPM801 also has protection and monitoring functions, suitable for systems that meet the functional safety requirements of ISO 26262 Automotive Safety Integrity Level (ASIL) D. These functions are integrated into a 5mm x 5mm VFQFN-32 package, saving PCB board area and minimizing the number of external components.

    The working voltage range of STPM801 is 4V-65V, which can withstand automotive electrical hazards at 25 μ A static current can minimize battery leakage when the vehicle is turned off. The target applications include area/body ECU, ADAS ECU, high-performance computing ECU, information entertainment ECU, redundant power supply system, and dual battery system.

    STPM801 has now been put into mass production.