ST reveals intelligent automotive circuit breaker
ST has commenced production of automotive high-side power switches with proprietary intelligent fuse protection and a serial peripheral interface (SPI) for diagnostic data, permitting enhanced resilience and functional safety.
The quad-channel VNF9Q20F is the first in a new family of monolithically integrated devices that combine ST’s advanced VIPower M0-9 MOSFET and proprietary STi2Fuse technology. Based on patented I2t (current squared through time-to-fuse) functionality, the STi2Fuse responds within 100µs to turn off the MOSFET if excessive current is detected.
Performing as an intelligent circuit breaker, the VNF9Q20F enhances boardnet voltage stability and prevents PCB traces, connectors, and wire harnesses from overheating. While guarding against damaging overloads, ST’s new automotive power switch also has a capacitive charging mode that allows harmless inrush currents and so permits normal operation with highly capacitive loads.
Ready for the latest zonal electrical/electronic architectures, the VNF9Q20F is also used for fuse and relay replacement, ECU isolation, and managing systems that are active when the vehicle is parked. With 64 programmable current-limit values, the STi2Fuse lets designers determine the overload response with high precision.
Internal features including a 10-bit analog-to-digital converter (ADC) and fault registers allow rich diagnostic information and digital current sense feedback to support vehicle capabilities such as predictive maintenance. By providing diagnostics through the SPI, and with built-in self-test, the VNF9Q20F enables systems to meet specified safety integrity levels in accordance with ISO 26262. An embedded failsafe mode preserves operational status in the event of a failure or malfunction.
