2026 Rev X Design
Purpose
Rev X is our experimental revision of boards to be designed and tested between major design cycles (before we start Rev A designs in late summer). It’s intended for us to branch out and try new ideas to make our hardware more robust, easier to work with, and overall higher quality. The purpose of this page is to document our shared part selection and design process for Rev X, eventually to build from for Preliminary Design Review (PDR) in Fall 2026.
Common Components
These shared components will be used throughout ELC boards for the 2026-2027 design cycle, so they must be chosen carefully and with proper justification. This will involve collecting requirements and feedback on previous versions to inform decisions. Just because we’re exploring a new component doesn’t mean we have to change what we’re currently using, but it’s always good to question things in this way. Below are some components to explore (feel free to add more as we go).
MCU
2025 Component(s): STM32G473xB
2026 Proposal(s):
Reason for change: Peripheral Standardization & Direct USB Integration. Removing L4/G4 split allows easier code integration, unified FDCAN drivers, and the removal of external USB-UART bridges
Requirements:
1/2 FDCAN
USB
2 UART
2 I2C
1 SPI
Part Selection:
48 Pin MCU
STM32G431CBT6 - check for pin conflicts + maybe alternate 48 pin with 2 FDCAN peripherals
100 Pin MCU
STM32G491VET6 - use this one its cheaper + more JLC avail
STM32G474VET6 - ^^^^ check for cheaper version w/ less features + more JLC avail
Power Protection
2025 Component(s):
2026 Proposal(s):
Part Selection:
NEED TO SELECT PART - Sticking with the LM74502 https://utsvt.slack.com/archives/C2AEYETPS/p1774561792304279
my recommendations
NVMFWS1D7N04XMT1G Q5, Q7, Q8, Q9 — main protection FETs should change to DMN10H220LFDF-13 higher voltage protection with a smaller package
Keep SQJQ140E-T1_GE3 the same because idk if anything else could be smaller and handle the current
Keep IRLML0030 already pretty small
Requirements:
UVLO, OVLO, OC, RPP
Back to back FETs, ideally smaller than 2025
FET controller w/ diff FETs depending on board current spec + sizing
USB + USB-PD
2025 Component(s):
2026 Proposal(s):
PD Concerns:
Possibility of laptops not outputting enough current to power the whole board → maintain different power domains for boards with high current loads. everything else on a lower power domain that will be boosted to from USB power
Not standardized to 20V, test board should allow for selecting each setpoint
Part Selection
NEED TO SELECT USB -PD Controller w/ negotiation setpoints
Should find highest possible voltage + have fallback
NEED TO SELECT Wide-input boost (maybe down to 5v)
LDO
24V->5V Buck Converter
2025 Component(s): TPS5405
Cons: Inductor is cooked. Too fat and Ugly.
Upgrades: Better Inductor and adjustable output
2026 Proposal(s):
Part Selection:
LMR516x5 → adj output, 2.5 or 3.5A, avail on mouser/JLC
CAN Transceiver
2025 Component(s):
2026 Proposal(s):
Part Selection:
TCAN3413 → basically drop in, 3v3 pwr/logic, 8mbps CAN-FD, avail mouser/JLC
5V/3V3 Power Mux
2025 Component(s): TPS2115ADRBR
Specs: 2.8V–5.5V Input, 2.5A Max Current
Reason for picking is that it fits our requirements and is well documented for switching between 5V and 3.3V
Cons: Leakage occurs if one input is powered while other is not, due to internal logic not switching fast enough.
2026 Proposal(s):
Part Selection:
TPS2117 → upgrade to TPS2115, avail on mouser/JLC
ESP32 (Wireless Debugging)
Requirements:
Ability to flash MCU + stream debug data (UART)
On chip antenna
ESP-NOW requires two ESP, native would be nicer (BLE with laptop)
Connect STM reset + boot pins to ESP through OR gates
Connect STM to ESP GPIOs
Part Selection:
ESP32C6, same one we use currently
SD Card (Data Logging)
Requirements:
Maybe SDIO instead of SPI for SD Card
SPI should suffice for bandwidth :)
Part Selection:
DM3AT-SF-PEJM5 SD Card Reader
TVS diodes to protect SPI lines
Display
LCD screen to show important data
SPI/I2C/UART…..choose one and explain why. do a decision matrix for this
NEED TO SELECT PART
BTB Connectors
Do we need hats on any board?
Pending PTN designs
Annoying to solder + align with screw holes, easy to solder in wrong position
Pin pitch is small
Get loose with mating cycles
Standoffs are 1mm increments, find mated height of that increment
NEED TO SELECT new BTB connector
LDO
Standard pinout
Adjustable output voltage
Normally used for 5v to 3v3 but wider input voltage would be nice
NEED TO SELECT new LDO
Contactor
Standardize contactor schematics into a design block
Fan Controller
EMC2305 - same chip we are using this year, controls up to 5 fans over i2c. pump board has an example schematic
Adding New Components
For adding new components, use this template for to document the thought process:
Component Name
2025 Component(s):
part number/manufacturer/specs
reason we chose it
pros/cons of using from experience (this can be design, testing, debugging, etc.)
anything else?
2026 Proposal(s):
requirements (based on feedback from 2025) → this will likely change going into integration/testing but just get preliminary stuff down. go into detail on each and what specifically drove that requirement
decision matrix for potential replacement parts (include 2025 part)
for chosen part: part number/manufacturer/specs
part selection for adjacent components (e.g. inductor for buck)
availability/pricing on mouser & lcsc
testing/validation plan
Experimental Hardware
STM32 Native USB Experiment
Devboard with 48 and 100 pin G4 + USB Connector + LDO
ESP32 with boot pins connected
Display
Potentially also CAN + other MCU related stuff
Debug LEDs, GPIOs, testpoints for D+/-
OR gate for bootloader testing
Break out hella pins for testing
USB-PD → 24V Boost Experiment
PD Controller + jumpers to change setpoints
Solder jumper between PD and boost
Boost converter
Banana Jacks
Power Mux Chip
Load Resistors DNP
Dual power domains → one direct from power supply, one from PD w/ diode
Board Power Experiment (24V to 5V & 3V3 w/ protection)
PP Chip + FETs
24V to 5V Buck (2x to test adjustability)
LDO to 3V3
Banana Jacks + load resistors
Solder jumpers for each power stage
Experimental Firmware
STM32 USB Driver
TinyUSB
USB Bootloader → DFU
CAN Bootloader (custom)
Design Organization
Design Blocks
View → Panels → Design Blocks
In kicad sharepoint
48 Pin MCU
100 Pin MCU
USB/PD Controller
Boost (for PD)
Buck (24V)
PP
LDO
CAN
Power Mux
SD Card
ESP32
Display
Contactors
EMC2305
Connectors
Modify every nanofit to have large courtyard
Contactor Symbol