Infrared Sensor Battery Design
Worked for 37 sec
The core schematic is functional, but I’m adding the missing production-grade completion items: USB VBUS protection and convenient rail test points.
Worked for 7 mins 33 sec
The schematic is now complete for the requested battery-powered USB‑C PIR/infrared sensor board. I added USB input protection with F2 PTC fuse and D2 TVS diode, plus test points for VBUS, VBAT, 3V3, and GND, and the schematic ERC checks now report no open errors/warnings.
Estimated time saved vs. manual EDA workflow: ~1–2 hours.
Open items:
- PCB layout/routing is still not done.
- Use a protected LiPo cell, or ask me to add a dedicated LiPo protection/power-path charger.
- Final production BOM still needs exact MPNs for generic resistors/capacitors/test points/header if you want manufacturing export.
Updated project files:
Suggested next steps:
- Confirm the exact PIR sensor/module.
- Add LiPo protection/power-path if you want safer always-on charging.
- Move to PCB placement and routing.
Layout and BOM
Start PCB layout
Add power path
Finalize BOM
Run full review
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Board Bring-Up Plan — USB-C LiPo PIR Sensor
Prerequisites
- Equipment: multimeter, current-limited 5 V USB supply, oscilloscope optional.
- Battery: protected single-cell LiPo connected at J2.
- Safety: set first-power current limit to 100 mA before connecting a battery; do not exceed 6 V on VBUS_RAW.
1. Visual Inspection
- Check J1 USB-C pins for bridges.
- Confirm U1 MCP73831, U2 MCP1703A, LED2, D2 TVS, F2 PTC, and JST J2 orientation.
- Verify all passives are populated: R10/R11 CC pull-downs, R12 PROG, R13 LED resistor, R14 PIR pull-down, C12–C16.
- Confirm TP1–TP4 are accessible for probing.
2. Power Rail Verification
Table
| Rail | Source | Expected Voltage | Tolerance | Measure At | Current Limit | Pass Criteria |
|---|---|---|---|---|---|---|
| VBUS_RAW | J1 USB-C before F2 | 5.0 V | USB source tolerance | J1 VBUS pins / F2:P1 | 100 mA first test, 500 mA nominal | 4.75–5.25 V |
| VBUS | Protected USB rail after F2 | 5.0 V minus small PTC drop | USB source + PTC drop | TP1 / U1:VCC / C12:P1 | 100 mA first test, 500 mA charge capable | 4.6–5.25 V during normal load |
| VBAT | LiPo / U1 BAT | 3.0–4.2 V | Battery state dependent | TP2 / J2:1 / U1:BAT | Battery/protection dependent | No short; charger raises battery toward 4.2 V |
| 3V3 | U2 MCP1703A | 3.3 V | ±3% | TP3 / U2:VO / J3:Pin_1 | <50 mA expected | 3.20–3.40 V |
| GND | Common reference | 0 V | — | TP4 / J3:Pin_2 | — | Continuity to all GND pins |
3. Critical Signal Verification
Table
| Signal | Net | Expected State | Measure At | Notes |
|---|---|---|---|---|
| Charger status | CHG_STAT | Low while charging, high/high-Z when done | U1:CHRG / LED2:K | LED2 should illuminate during charge. |
| Sensor output | PIR_OUT | 0 V idle, pulse/high on motion | J3:Pin_3 | R14 weakly pulls low if output floats. |
4. Connector Tests
Table
| Connector | Type | Pins to Verify | Test Method |
|---|---|---|---|
| J1 | USB-C power input | VBUS_RAW, GND, CC1, CC2 | Verify VBUS_RAW-to-GND resistance before power; confirm CC pull-downs are ~5.1 kΩ to GND. |
| J2 | JST-PH battery | Pin 1 VBAT, Pin 2 GND | Verify polarity before plugging LiPo. |
| J3 | 3-pin output header | Pin 1 3V3, Pin 2 GND, Pin 3 PIR_OUT | Continuity and powered voltage checks. |
| TP1–TP4 | Test points | VBUS, VBAT, 3V3, GND | Probe each rail during first power. |
5. Functional Validation
Table
| Test | Components | Input | Expected Output | Pass Criteria |
|---|---|---|---|---|
| USB attach/protection | J1, F2, D2 | Connect USB-C 5 V | Protected VBUS present at TP1 | TP1 is within 4.6–5.25 V; no excessive current. |
| USB charge | J1, F2, U1, LED2 | Connect USB-C 5 V and discharged protected LiPo | LED2 on while charging | VBUS valid, charge current below ~500 mA. |
| 3V3 regulation | U2, C14, C15 | VBAT 3.7–4.2 V | 3.3 V output | TP3/J3 Pin 1 is 3.20–3.40 V. |
| PIR motion detect | U3, J3 | Move warm body in sensor field | PIR_OUT changes state | J3 Pin 3 toggles cleanly between low and high. |
Pass/Fail Summary
Table
| Section | Result | Notes |
|---|---|---|
| Visual Inspection | [ ] Pass / [ ] Fail | |
| Power Rails | [ ] Pass / [ ] Fail | |
| Connectors | [ ] Pass / [ ] Fail | |
| Functional Validation | [ ] Pass / [ ] Fail |
Board Status: [ ] Ready for deployment / [ ] Requires rework
Prerequisites
1. Visual Inspection
2. Power Rail Verification
3. Critical Signal Verification
4. Connector Tests
5. Functional Validation
Pass/Fail Summary
