size_hold_up_capacitor
Read-onlyIdempotent
Size an MLCC reservoir bank for a brown-out ride-through window in EFFECTIVE farads, then report the marked value you must actually buy.
Instructions
Size an MLCC reservoir bank for a brown-out ride-through window in EFFECTIVE farads, then report the marked value you must actually buy. Solves C = I·t/ΔV for the required effective capacitance and divides by the retention at the worst-case bias in the window, because sizing from the marked value is how a design that 'passes' delivers 0.85 ms of hold-up when the spec asked for 20 ms. Reports the achieved hold time, the shortfall, and the required marked capacitance.
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| rated_v | No | Capacitor rated voltage. Defaults to 2x v_start to keep bias derating near 50%. | |
| v_floor | Yes | Minimum voltage the load tolerates (brown-out floor), in volts. | |
| v_start | Yes | Rail voltage at the moment the source collapses, AFTER any ORing diode drop — not the nominal input. | |
| ambient_c | No | Operating ambient in °C. | |
| case_size | No | EIA case code (0402/0603/0805/1206/1210). | 0805 |
| dielectric | No | EIA dielectric: X5R, X7R, X8R, C0G/NP0. | X5R |
| tolerance_pct | No | Capacitance tolerance in percent. | |
| load_current_ma | Yes | Load current drawn from the reservoir during the outage, in mA. | |
| hours_in_service | No | Expected service life in hours. | |
| required_hold_time_ms | Yes | Required ride-through duration in milliseconds. |
Output Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| notes | Yes | Human-readable findings: which term dominates, what to change, and any caveat. | |
| passes | Yes | True when achieved meets or exceeds required. | |
| v_floor | Yes | Brown-out floor the rail must stay above. | |
| v_start | Yes | Rail voltage at the start of the outage, after any diode drop. | |
| margin_ms | Yes | Achieved minus required; negative means the design fails. | |
| shortfall_uf | Yes | Effective capacitance still missing; zero when the design passes. | |
| load_current_ma | Yes | Load current used. | |
| achieved_hold_time_ms | Yes | What the sized bank actually delivers. | |
| marked_capacitance_uf | Yes | The reel value you must buy to get that effective value. | |
| required_hold_time_ms | Yes | The spec: how long the rail must survive. | |
| required_capacitance_uf | Yes | Effective capacitance the physics demands (I·t/ΔV). | |
| effective_capacitance_uf | Yes | Effective capacitance the sized part delivers. | |
| required_marked_capacitance_uf | Yes | Alias of marked_capacitance_uf, kept for clarity. |