12 V to 5 V / 1 A Buck Molecule (TPS54202)

@@ -0,0 +1,159 @@+# The same buck, built by AI in Autodesk Fusion 360++The main page of this project builds the TPS54202 buck in KiCad. This page is the second run: the same brief, built as a complete board in **Autodesk Fusion 360** by Claude, driven by [Adom AI Flow](https://wiki.adom.inc/adom/adom-aiflow) inside [Adom Hydrogen](https://wiki.adom.inc/adom/hydrogen), with the [Fusion Bridge](https://wiki.adom.inc/adom/fusion-bridge) doing the clicking in Fusion. It is the build behind the video "AI PCBs in Fusion 360".++One sentence went in. A routed, poured, analysed board with Gerbers, a BOM and a pick-and-place file came out.++## At a glance++| | |+|---|---|+| The prompt | "Use adom-aiflow to design a 12 V to 5 V, 1 A buck converter using the TPS54202, and build it as a complete board in Autodesk Fusion." |+| The AI | Claude Code on Claude Opus 5.5, in Hydrogen |+| Prompt to finished board | 2 h 42 min, 21 steps, 4 loop-backs, none skipped |+| Design check | 0 errors, 0 unconnected |+| Current | peak 53 A/mm² across the copper, 0 issues |+| Heat | U1 rises 49 °C in still air (28.5 °C with airflow) |+| Board | 28 x 20 mm Adom molecule, 2 layers |+| Out of the run | Gerbers, BOM and pick-and-place (CPL) |++## The tools++| tool | what it did here |+|---|---|+| [Adom Hydrogen](https://wiki.adom.inc/adom/hydrogen) | The workbench: VS Code and Claude on the left, web views (timeline, wiki, SPICE, Fields) on the right. |+| [Adom AI Flow](https://wiki.adom.inc/adom/adom-aiflow) | The run itself: plans the 21 steps, checks each one, and sends Claude back when a step fails its check. |+| [Fusion Bridge](https://wiki.adom.inc/adom/fusion-bridge) | Drives Fusion 360 on a Windows PC from the cloud: sign-in, library, schematic, board, exports. |+| [Adom wiki component pages](https://wiki.adom.inc/adom/tps54202ddcr) | Where every part comes from: symbol, footprint, a checked 3D model and distributor numbers. |+| Adom SPICE | ngspice in the container, with LTspice and PSpice for TI one click away. |+| [Adom Fields](https://wiki.adom.inc/adom/adom-fields) | Current density and heat on the real copper. |++## The run, step by step++### 1. One prompt++![The prompt typed into Claude Code in Hydrogen](img/01-prompt.jpg)++The whole request is one sentence typed into Claude Code in Hydrogen. Naming `adom-aiflow` is what turns it into a measured run instead of a chat.++### 2. The AI Flow timeline++![The AI Flow timeline with its 21 steps and the loop-back arcs](img/02-timeline.jpg)++AI Flow lays the job out as 21 steps, from intake to the finish line, and keeps a live clock. Each arc on the left is a loop-back: a later step found a problem and sent Claude back to an earlier one. This run had four.++### 3. Parts from the Adom wiki++![The TPS54202DDCR wiki page with its 3D model loaded](img/03-wiki-part.jpg)++Every part comes from its Adom wiki component page: a 3D model checked Z-up, the symbol and footprint, and Mouser, DigiKey and LCSC numbers.++![The IN-S63BTG LED page, its states widget switched to lit](img/04-led-states.jpg)++The LED's page carries one 3D model per state, off and lit, so a viewer or a probing simulation shows the part as it should look.++### 4. The bridge signs in to Fusion++![The Autodesk sign-in page, driven by the Fusion Bridge](img/05-signin.jpg)++The PC used for this step wasn't signed in to Fusion yet, so the Fusion Bridge drove the sign-in itself: Fusion's Sign in button, then the Autodesk page in the browser. It never types a password or a 2FA code; those stay with the person.++![Fusion's Active Sessions Exceeded dialog, with the bridge choosing to suspend the other seat](img/06-seat.jpg)++The license seat was still on another PC, so the bridge moved it: suspend Fusion there, continue here.++### 5. One project library++![The TPS54202 symbol in the Fusion library](img/07-library-symbol.jpg)++![The TPS54202 footprint in the Fusion library](img/08-library-footprint.jpg)++AI Flow builds one Fusion library for the project: a symbol, a footprint and a bound 3D model for every part, the TPS54202 symbol drawn with its chip outline.++### 6. The schematic++![The schematic drawn in Fusion, in labelled groups](img/10-schematic.jpg)++Claude draws the schematic live in Fusion in labelled groups, and every pin is checked against the netlist.++### 7. SPICE++![Adom SPICE: soft start, the load step and the inductor current](img/11-spice.jpg)++ngspice runs in the container: the soft start from 12 V, a step from 0.5 A to 1 A, and the inductor current through both.++### 8. Placement, and the first loop-back++![C5 in its first spot, ringed](img/12-placement-loop.jpg)++The router's check found the switch-node trace detouring 18.9 mm because of where C5 sat, so AI Flow sent Claude back to placement.++![C5 in its new spot, beside the switch pin](img/13-placement-fixed.jpg)++C5 moved next to the pins it serves. A second loop-back turned R6 so its pad faces the output feed.++### 9. Routing, heatsink vias and pours++![The routed board with its pours](img/14-routed.jpg)++The board is routed to 100 percent, then the heatsink vias, the pours and the rounded corners each land as their own checked pass. A review of the vias then found U1 had only 1 of its 6 planned heatsink vias, and AI Flow sent Claude back to routing: clear the copper, re-route around U1, place the full array, pour again. The six vias now tie U1's ground pin to the bottom ground plane, all within 2.75 mm.++![The GND pour highlighted](img/16-pour-gnd.jpg)++![The SW pour highlighted](img/17-pour-sw.jpg)++Each pour net in turn: GND, then the small solid SW patch.++### 10. Current and heat++![Adom Fields: heat on the board in Hydrogen](img/15-fields.jpg)++Adom Fields solves the real copper for current density and temperature. Peak current density is 53 A/mm², and the vias carry about a third of U1's 0.25 W into the plane.++### 11. Silkscreen++![The finished silkscreen in Fusion](img/18-silkscreen.jpg)++Framed tags on every edge contact, matched frames on the corner pins, and each value in small text beside its reference. The silkscreen rules that came out of this run (frame sizes, equal widths, minimum text heights per fab) are now part of AI Flow's silkscreen skill.++### 12. The board in 3D++![The finished board in Fusion's 3D view](img/19-3d-board.jpg)++Every part sits flat on its pads in Fusion's 3D view.++### 13. The finish line++![The timeline at 21 of 21: Gerbers, BOM and CPL exported](img/20-finish.jpg)++21 of 21 steps, the finish line reached: Gerbers, BOM and pick-and-place exported.++## What it cost++One run on Claude Opus 5.5, prompt to finished board, 2 h 42 min. Measured from the run's own session log and Claude's plan usage meter:++| plan | cost of this run |+|---|---|+| API (pay per token) | about $24 |+| Max 20x ($200/month) | about 4 % of a week, about $1.85 |+| Max 5x ($100/month) | about 16 % of a week, about $3.70 |+| Pro ($20/month) | about 80 % of a week, about $3.70, with waits for the limit to reset |++The API figure is 203 k output tokens, 83 M cached input tokens read and 453 k written, at Opus 5.5 list prices.++## After the run++- **Silkscreen:** the pass shown in step 11 was finished after the run, one tag at a time.+- **Test points:** TP5 came off the board; its ground probe moved to J5 pin 1.+- **Final check:** 0 errors and 0 airwires, saved as the final cloud version, and the fab files were exported again.+- **Hottest spot:** 57 °C rise in still air against a 55 °C budget. A 28 x 20 mm board shedding 0.37 W into still air is limited by its size, not its layout.+- **Sourcing:** the TPS54202 was out of stock at Mouser and DigiKey when this was built (140-day lead), so order it early.++## How the video was made++- **Capture:** the whole run was recorded on the Windows desktop at 2560 x 1440 with Adom Bridge's built-in recorder, about 2 h 50 min of footage.+- **More than one PC:** Hydrogen drives several Windows PCs as one mesh. The run happened on one. The opening prompt, the sign-in, the library and the wiki pages were re-shot afterwards, some on other PCs, so the main take stayed untouched.+- **The cut:** a script cuts about 50 shots from the footage, sizes each one to its narration line, and renders every zoom with smooth sub-pixel motion. The rings and arrows that point at C5 and R6 are drawn on top in brand teal.+- **The cost scene:** a slow walk around the finished board, rendered natively in Fusion, behind the numbers above.+- **The thumbnail:** the board is a render from Fusion, placed over a screenshot of the same board in Fusion's 2D editor.+