SiC automotive e-fuse demo disconnects up to 30A 900V

SiC automotive e-fuse demo disconnects up to 30A 900V

“The demonstrator can detect and interrupt fault currents in microseconds, 100 – 500 times faster than traditional mechanical approaches,” according to the company. “The fast response substantially reduces peak short-circuit currents from tens of kilo-amps to hundreds of amps, which can prevent a fault event from resulting in a hard failure.”

SiC automotive e-fuse demo disconnects up to 30A 900V

It “provides designers with a SiC-based solution to jump-start their development”, added Microchip v-p of SiC Clayton Pillion. “The solid-state design alleviates long-term reliability concerns about electromechanical devices because there is no degradation from mechanical shock, arcing or contact bounce.”

The demo board, which is described as an ‘auxiliary e-fuse design’ and is therefore not aimed at the main traction inverter, comes in six versions spanning 400 or 800V batteries, and 10, 20 or 30A circuits.

SiC automotive e-fuse demo disconnects up to 30A 900V

Current detection is staged, with a comparator-based purely hardware circuit detecting high current (100 – 200A, so short-circuits) faults in a microsecond. From there down to ~45A for more sophisticated control of currents, a slower firmware loop in a PIC microcontroller reacts in around a millisecond.

Below there, junction temperature estimation is used as a current-limiting metric to protect the e-fuse from over-heating. Estimation is based on a thermistor-based temperature measurement, the heatsink’s thermal capacity and drain current – modelled with a first-order infinite impulse response (IIR) digital filter.

A LIN bus is included for control and monitoring.

“The LIN interface enables the configuration of the over-current trip characteristics without the need to modify hardware components, and it also reports diagnostic status,” said Microchip. “With the e-fuse demonstrator’s resettable feature, designers can package an e-fuse in the vehicle without design-for-serviceability constraints.”

The board needs its own 9 – 16V supply (<100mA), and operates in ambients between -40 and +85°C.

Software support and debug comes via the MPLAB X IDE (integrated development environment), and there is a LIN serial analyser development tool for PCs.

There is an e-fuse demo product page, but much of the assocaited information is ‘on request’ only. This user guide has some good extra information

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