Sensor Device BOM Design
Working for 2 days 20 hrs...
Thought for 10 sec
1/4 Check and clean dangling traces before routing
Accessed knowledge for the next task.
Thought for 3 sec
Completed Dangling Traces check — found 270 issues.
Thought for 4 sec
2/4 Run auto-route
Accessed knowledge for the next task.
Thought for 5 sec
Routing complete!
Thought for 6 sec
3/4 Run DRC focused on airwires and clearance after routing
Check and clean dangling traces before routing
Run auto-route
Run DRC focused on airwires and clearance after routing
Summarize routing DRC issues and next fixes
Accessed knowledge for the next task.
Thought for 4 sec
Running 8 design checks.
Read layout...
continue routing
Route all unrouted nets on this PCB
On it...
Refine this doc
Ask about this doc
Power Budget — EU Smart Environmental Sensor Node
Source and Assumptions
- Battery: RRC2054-2 smart Li-ion pack, 14.4 V nominal, 97.92 Wh.
- Buck regulator efficiency assumption for early sizing: 85% as provided in the user BOM.
- Average power values are from the user BOM and must be replaced with datasheet-verified operating currents during detailed schematic finalization.
- CO2 peak pulse: 413 mW from user BOM.
- IR burst: 140 mW per LED at 100% burst-equivalent, 1% duty used for average in the BOM. Design allows up to four LEDs.
Average Power from User BOM
Table
| Load | Budget power |
|---|---|
| STM32WBA65PII7 MCU/radio | 8 mW |
| EC Sense NH3 TB200B-ES1-NH3-100-I2C | 40 mW |
| Senseair Sunrise CO2 | 0.112 mW average, 413 mW peak |
| Bosch BMV080 PM sensor | 3.1 mW average at 1 sample / 10 min |
| Bosch BME280 | 0.012 mW |
| TSL25911FN light sensor | 0.83 mW active |
| IM69D127V11XTMA1 PDM mic | 1.76 mW |
| Bosch BME688 | 2.97 mW low-power gas mode |
| VD55G4 camera | 0.9 mW standby, ~35 mW active |
| SFH 4045N IR LEDs | ~1.4 mW average each at 1% duty, ~140 mW burst each |
| LIS2DW12TR | ~0.0007 mW low-power wake |
| BGT60LTR11AIP radar | ~5.6 mW budgeted |
Average System Power Estimate
Using four IR LEDs and camera active budget:
- Non-IR average sensor/controller total: 93.2847 mW
- IR average total: 4 × 1.4 mW = 5.6 mW
- Total average load power before regulator loss: 98.8847 mW
- Reflected battery input power at 85% efficiency: 116.335 mW
- Average battery current at 14.4 V nominal: 8.08 mA
- 30-day energy estimate: 0.116335 W × 720 h = 83.76 Wh
- RRC2054-2 nominal pack reserve against this estimate: 97.92 Wh / 83.76 Wh = 1.17×
Peak/Burst Sizing Estimate
Dominant peak loads:
- CO2 peak pulse: 413 mW
- Four IR LEDs burst: 4 × 140 mW = 560 mW
- Baseline non-IR average with camera active: 93.2847 mW
- Estimated simultaneous burst output power: 1.066 W
- Reflected battery input power at 85% efficiency: 1.254 W
- Peak battery current at 14.4 V nominal: 87.1 mA
Rail Sizing Guidance
- 5V0 rail must support NH3 sensor, CO2 peak pulse, any 5 V sensor interface, and IR LED driver input if LEDs are powered from 5V0.
- 3V3 rail must support STM32WBA, BME280, BME688, TSL25911, LIS2DW12, BGT60LTR11AIP interface/domain, BMV080 if operated at 3V3, camera digital domain if applicable, and level shifters.
- 1V8 rail required for IM69D127V11XTMA1 microphone and any camera/radar low-voltage IO domains verified by datasheets.
- ST L6982N50DR at 2 A and ST L6981N33DR at 1.5 A have large margin against the initial average and peak estimates, but their datasheet application circuits, inductor saturation current, compensation, layout, and output-capacitor derating still must be followed.
Risks / Follow-up
- Sensor average currents depend strongly on firmware duty cycle and sampling schedule.
- Camera and radar operating modes can dominate energy if not aggressively duty-cycled.
- CO2 and IR bursts require local bulk capacitance near the loads.
- A 30-day target is plausible only with strict duty cycling and low sleep current; regulator quiescent current must be included after datasheet extraction.
Source and Assumptions
Average Power from User BOM
Average System Power Estimate
Peak/Burst Sizing Estimate
Rail Sizing Guidance
Risks / Follow-up
