Overview
Custom power distribution module replacing the fuse/relay box on our FSAE car. Nine Infineon BTS7004-1EPP PROFET+2 high-side switches drive the ECU, ignition, injectors, fuel pump, dash, radiator fan, water pump, and two aux channels — each with the PROFET’s built-in current-sense feedback, on-board thermal monitoring, and a Teensy 4.1 controller on CAN.
Built in Altium (PDM_V0.PrjPcb, Montana FSAE 26-27 workspace) from a KiCad
import: 274 components, 161 nets, 10 schematic sheets.
Switching
Nine BTS7004-1EPP single-channel PROFET+2 (4 mΩ, PG-TSDSO-14) replace the relay/fuse box. Three channels (fan, water pump, aux) are PWM-capable with pot-driven manual override and a hardware enable path through a 74HC32, so cooling still runs if firmware hangs. One CB1-P-12V resettable breaker stays in the design as a mechanical backstop, with per-channel blade/cartridge fusing behind each PROFET.
Current sensing
Each channel’s PROFET IS pin feeds the Teensy for per-channel load current and open-load / overcurrent diagnostics. Total-pack current is measured separately by an INA226 across a 0.5 mΩ Kelvin shunt (HCSK1216), with an INA260 on a second rail.
Thermal monitoring
Three TMP1075D digital temperature sensors sit across the PROFET bank, sharing the I²C bus with the current monitors and address-strapped to 0x48 / 0x4B / 0x4F so all three read out independently — ±1 °C over the automotive range, with no analog thermistor chain and no ADC channels burned. Firmware uses them to derate or shed channels before the PROFETs reach their own thermal shutdown, and to spin up the board fan, which runs on its own PWM’d, separately fused low-side channel so the module’s cooling is independent of the vehicle loads it switches.
Input protection
An LTC4367 surge stopper (overvoltage / undervoltage / reverse) sits ahead of an LM74700 ideal-diode controller driving SiDR626LDP PowerPAK FETs, plus an SMCJ26CA TVS on the 12 V input. SRV05-4 arrays and an SZNUP2105L protect the signal and CAN lines.
Rails
12 V battery in, with Recom drop-in switchers for logic: R-78B5.0-1.0 (5 V) and R-78C3.3-2.0 (3.3 V). Star ground with power and signal domains kept separate.
Communications & connectors
A TJA1051T-3 transceiver puts the PDM on the vehicle CAN bus, DBC-first so the PDM, Speeduino/Haltech ECU, and dash all agree on the message set. I²C carries the INAs and the TMP1075Ds, plus a 4-pin JST display connector. Power outputs land on 2 × Molex Mega-Fit 2x06; dash and ECU inputs on 2 × Micro-Fit 2x03; CAN and fan taps on JST GH.