Four-channel high-side driver with SPI diagnostics
The BTS54220LBAAUMA1 is a 4-channel high-side power switch from Infineon, built for automotive loads that need current monitoring and fault reporting. Each output drives an N-channel MOSFET with a typical on-resistance of 9 mOhm on the lower-Rds(on) channels and 27 mOhm on the higher-Rds(on) pair — the split lets you assign the low-resistance channels to high-current loads like relays or solenoids and the higher-resistance ones to lamps or LEDs where the extra milliohms don't cost you headroom.
AEC-Q100 and the 150 °C junction ceiling
That puts it in the under-hood and engine-bay class, where ambient temperatures can hit 125 °C and the die sees the full thermal load from the pass element. The 24-PowerTDFN (PG-TSON-24-3) package has an exposed pad that needs a good thermal via pattern to the ground plane; without it the junction temperature will climb above the 150 °C ceiling under continuous 3 A loads.
SPI interface and fault protection set
Unlike a basic high-side switch that just turns on and off, this part talks back over SPI. The interface lets the MCU read the output status, detect open-load or short-to-battery conditions, and adjust the slew rate (the slew-rate-controlled feature is built in). The protection block covers current limiting (fixed threshold), over-temperature shutdown, over-voltage clamp, and under-voltage lockout on the logic supply — so a single fault event won't cascade into a dead rail.