USB-C Wi-Fi BLE Sensor Node Design

flux

I set up the project and converged the schematic architecture, but I could not finish wiring because execution credits ran out.
Done so far:
  • Renamed the project to USB-C Wi-Fi BLE Env Sensor Node and updated the description.
  • Chose the core architecture:
    • MCU: ESP32-C3-MINI-1-N4
    • T/RH sensor: Sensirion SHT41-AD1B-R2
    • USB-C input connector: GCT USB4215-03-A
    • Input protection / power-path: TI TPS25940L eFuse for reverse blocking, OVP, UVLO, and OCP
    • 3.3 V regulator: TI TPS62821 buck converter instead of an LDO, because the ESP32-C3 radio peaks make a small 5 V → 3.3 V LDO thermally marginal
    • USB ESD: identified suitable USB data-line protection parts such as USBLC6-2SC6 / TPD2EUSB30A
  • Verified key datasheet constraints:
    • ESP32-C3-MINI-1-N4: 3.0–3.6 V supply, Wi-Fi TX peak up to about 350 mA, BLE TX peak up to about 340 mA, deep sleep about 5 µA, USB on GPIO18/19, strapping on GPIO2/8/9, GPIO9 needs pull-up.
    • ESP32 hardware guidance: use at least 500 mA-capable 3.3 V rail, EN must not float, recommended 10 kΩ + 1 µF RC on EN, USB series resistors 22/33 Ω, antenna keepout at board edge.
    • SHT41: 1.08–3.6 V, I2C, fixed 0x44 address, idle about 80 nA, measurement current about 320–500 µA.
    • TPS25940L: 2.7–18 V input, programmable UVLO / OVP / current limit, reverse current blocking, open-drain fault output.
    • TPS62821: 2.4–5.5 V input, 1 A output, 4 µA quiescent current, recommended 470 nH inductor, 4.7 µF input, 2×10 µF output, adjustable output via resistor divider.
Power-budget decision:
  • The node is comfortably under a 500 mA USB source on average, even with Wi-Fi active.
  • A simple LDO would dissipate too much heat during high-radio activity, so the buck converter is the correct choice for a consumer design.
What remains:
  • Add all components to the schematic.
  • Wire:
    • USB-C CC pull-downs
    • USB VBUS entry protection and ESD
    • TPS25940L thresholds / current limit network
    • TPS62821 feedback network and passives
    • ESP32-C3 support parts, boot/reset, USB resistors
    • I2C pull-ups and SHT41 decoupling
    • optional status LED / debug header
  • Run review/ERC and fix any issues.
  • Create project files with the power budget and bring-up notes.
If you want, I can continue from this exact architecture in the next run: ESP32-C3-MINI-1-N4 + SHT41 + USB4215-03-A + TPS25940L + TPS62821.
Add and wire power
Add debug features
Set protection limits
Document design notes
Run ERC review
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    USB-C Wi-Fi BLE Env Sensor Node

    USB-C Wi-Fi BLE Env Sensor Node thumbnail
    Consumer USB-C environmental sensor node using a low-power Wi-Fi + Bluetooth MCU and digital temperature/humidity sensor. Powered from 5 V USB-C sink input with input protection including reverse blocking, OVP, UVLO, and overcurrent limiting, then regulated to 3.3 V for the radio and sensor.

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