| Board | HW-131 Breadboard Power Supply |
| Part number | AMS1117-3.3 |
| Vendor | Advanced Monolithic Systems |
| Package | SOT-223 |
| Domain | Power · LDO |
| Scenario | Marginal ripple |
| Backend | mock |
| Bench | Simulator |
| TP | Check | Limit | Measured | Outcome |
|---|---|---|---|---|
| tp1 | Output voltage (500 mA load) | — | 3.3022 V | PASS |
| tp2 | Output voltage (no load) | — | 3.3048 V | PASS |
| tp3 | Output ripple (500 mA load) | — | 0.0481 V | FAIL |
High output ripple, DC regulation clean — output capacitor.
Output ripple measured [TP3: 0.048 V] pp against a 15 mV limit (3.2× over spec).
DC output voltage is within spec at every load point [TP1: 3.302 V], [TP2: 3.305 V], so the pass device, the reference and the feedback loop are healthy. A ripple-only failure of this magnitude points to the output capacitor — most likely an under-valued or high-ESR COUT, or poor placement near the regulator.
| Root cause | Output capacitor — high ESR or under-valued |
| Next step | Verify the COUT value and ESR against the datasheet's stability requirements, then re-test. |
| Confidence | 86% |