ST’s VNF1248F automotive e-fuse controller targets 48 V power distribution
STMicroelectronics has expanded its STi²Fuse family with the VNF1248F automotive e-fuse controller, a device aimed at protecting wire harnesses and managing power distribution in 12 V, 24 V, and 48 V boardnets. The VNF1248F automotive e-fuse controller combines fast electronic protection with flexible configuration to support zonal architectures and relay replacement in modern vehicles.
For eeNews Europe readers, this is potentially relevant as 48 V boardnets and electrified powertrains are pushing designers towards solid-state protection that can be tuned, monitored, and integrated into functional-safety concepts rather than relying on fixed wire fuses.
Fast electronic protection for 48 V architectures
According to ST, the VNF1248F reacts within 100 µs, faster than a conventional wire fuse, which potentially helps limit fault propagation on the harness in case of short circuits or overloads. The device adds a capacitive charging mode (CCM) intended to handle large capacitive loads with high inrush current, a common challenge in 48 V zones with DC/DC converters, inverters, and other high-energy loads.
For parked or low-power modes, the controller provides an enhanced Standby-ON mode with up to 600 mA current capability while keeping its own consumption below 75 µA, which can support always-on loads without significantly impacting battery state of charge. An optional external logic-supply pin can, according to ST, reduce power consumption by about 0.4 W in 48 V systems, while an LV124-compliant battery undervoltage shutdown function aims to keep system behaviour predictable across supply dips.
ST positions the device for power distribution in zonal vehicle electrical architectures, fuse and relay replacement, ECU main switching and “always-on” circuitry supply. The controller is supplied in a 5 mm x 5 mm QFN-32 package and is in production; indicative pricing starts at $2.63 for 1,000-piece quantities.
Functional safety, configurability and tools
The VNF1248F is designed to support ISO 26262 functional-safety concepts by integrating fault-detection and reaction mechanisms, including fail-safe and limp-home modes. Dedicated diagnostics, built-in self-tests and a hardware pin for direct control of the external MOSFET gate in case of microcontroller failure are intended to help designers reach higher ASIL targets in domains such as body, chassis or powertrain control.
Configuration is handled via an SPI interface to a host microcontroller, allowing parameters such as hard short-circuit latch-off behaviour, current-versus-time fuse emulation and MOSFET desaturation shutdown to be set in software rather than with external components. On-chip non-volatile memory stores an immutable default configuration, so the e-fuse can revert to a defined behaviour in failsafe or locked states without relying on software initialisation.
To support evaluation, ST offers the EV-VNF1248F board, which is pre-assembled for direct connection to load, supply and microcontroller, together with the STSW-EV-VNF1248F software package. The latter provides a graphical user interface and firmware running on an EV-SPC582B board to configure and monitor the VNF1248F, which may shorten bring-up for teams assessing solid-state fuse strategies in 48 V and multi-voltage automotive platforms.
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