What this low-side switch does in the assembly
The Infineon BTS3028SDRATMA1 is a single-channel N-channel low-side switch from the HITFET® family. It drives resistive, inductive, or lamp loads up to 5 A continuous from a 60 V max supply rail. The gate is self-biased from the load voltage — no separate Vcc pin needed, which cuts one rail from the power tree. Typical Rds(on) is 28 mOhm, so at 5 A the conduction loss sits around 0.7 W. That fits the TO-252-3 (DPak) package with the tab soldered to a reasonable copper area on the PCB.
Fault protection — built in, no external parts
The BTS3028SDRATMA1 integrates current limiting (fixed threshold), over-temperature shutdown, and over-voltage clamping. No external sense resistor, no comparator, no TVS across the switch — the die handles it. That shrinks the BOM count and board area for a protected low-side driver. The output is a single N-channel MOSFET with a 1:1 input-to-output ratio. Input type is non-inverting, so a logic high on the gate turns the load on. Interface is simple on/off — no PWM or diagnostic feedback on this variant.
The 150 °C junction temperature ceiling matches automotive under-hood and industrial motor-drive environments. Package is the TO-252-3 (DPak) with two leads plus the tab, surface-mount. The supplier device code is PG-TO252-3-11.