seveibar/f1c1990s-dev-board

This code manages the entire PCB assembly process for a computer hardware module, including component placement, schematic integration, automated routing, copper pouring, and design rule checks, focused on a four-layer carrier board with integrated support components and connectors.

Version
1.8.0
License
unset
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modules/f1c100s/docs/bulk-capacitors.md

> The dev board uses the modified **native** profile with all components on top. Other layout profiles retain their previously published two-sided layouts.

# Bulk capacitor selection

All seven rail reservoirs use 0805 land patterns on the top of the module. The three 10 µF TV/reference filter capacitors also use 0805 top-side footprints. Dedicated 100 nF processor decouplers remain on top with their direct pin branches. This is a single-sided component assembly.

| Role | Part | Nominal | Rating | Dielectric | Typical capacitance under DC bias |
|---|---|---|---|---|---|
| Six rail reservoirs and three TV/reference filters | GRM21BR61E106KA73L | 10 µF | 25 V | X5R | 7.21 µF at 3.3 V; 9.50 µF at 1.8 V |
| DRAM rail reservoir | GRM219R71E105KA88D | 1 µF | 25 V | X7R | 0.978 µF at 1.8 V |
| Six carrier regulator input/output reservoirs | GRM21BR71C475KE51L | 4.7 µF | 16 V | X7R | 3.31 µF at 5 V; 4.13 µF at 3.3 V |

The carrier regulator reservoirs remain on top and also use 0805 footprints. Capacitance values are unchanged from the original circuit. Larger packages do not guarantee the full nominal capacitance in service.

Typical values were interpolated from Murata's product-characteristics API on 2026-09-13 at 25 °C, with 1 Vrms test amplitude for the 10 µF and 1 µF parts and 0.5 Vrms for the 4.7 µF part. These are typical model results, not guaranteed minima; tolerance, temperature, aging and operating AC amplitude also matter. No PDN simulation or hardware measurements have been performed.

Sources: [10 µF part](https://pim.murata.com/en-us/pim/details/?partNum=GRM21BR61E106KA73%23), [1 µF part](https://pim.murata.com/en-us/pim/details/?partNum=GRM219R71E105KA88%23), [4.7 µF part](https://pim.murata.com/en-us/pim/details/?partNum=GRM21BR71C475KE51%23). Each product page exposes the C–DC-bias curves used here.

## Dev-board single-sided assembly revision

The native profile in this vendored copy places all bulk and reference capacitors on top. It replaces the earlier underside placement; capacitor values, 0805 sizes, voltage ratings and the dedicated 100 nF decouplers are retained. Stored routing is regenerated for the new placements.