12 V to 5 V / 1 A Buck Molecule (TPS54202), built in Altium Designer

A 12 V to 5 V, 1 A synchronous buck on the TI TPS54202, built as a complete board in Altium Designer from one sentence typed into Claude Code inside Adom Hydrogen:

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 Altium Designer.

This is part 3 of the series: the same brief as John's KiCad build and the Fusion 360 build. The AI was Claude Opus 5.5 running Adom AI Flow. It drove Altium Designer 26.11.1 on a Windows PC through the Altium Bridge, one edit at a time, each read back from the live board. Nobody touched Altium during the run. It took 1 h 48 min from the prompt to a finished board, Gerbers included.

The board has not been fabricated. Everything below is design, simulation and analysis.

Revision 2 (2026-10-20). Two fixes after the run, made through the Altium Bridge:

• TP1 moved 0.2 mm left. AI Flow 0.2.9's courtyard check found it inside L1's courtyard by 0.15 mm. It is still on the switch node, its traces follow it, the board is repoured, and Altium's DRC shows no clearance or connection errors.
• The schematic is redrawn with the corrected TPS54202 symbol. The pins now start on the symbol's box, with the pin names inside it; Altium Bridge 0.2.51 fixed the symbol generator. The sheet compiles to all 10 nets, pin for pin.

The manufacturing files, the Gerber renders and the 3D model are regenerated from revision 2.

Gallery

The routed and poured board in Altium Designer's 2D view.	The schematic (revision 2), on Altium's own sheet template.
The prompt, as sent.
The top, drawn from the exported Gerbers.	The bottom, mirrored as seen with the board flipped over.
Adom Fields: the current through the copper and vias, solved on this board.	ngspice loop gain at 12 V with 0, 47, 68 and 100 pF feed-forward.

Key specs

Open items before ordering

These are findings from the run and from making its video. They are listed here rather than hidden:

• The board thickness. The Altium project kept Altium's default layer stack, a 0.4 mm board. The design and the heat analysis assume 1.6 mm FR4: set the stack, or put 1.6 mm and 1 oz copper on the fab order.
• The switch node. It is 18.2 mm of copper against a 12 mm budget. U1's switch pin and L1 are further apart than in the KiCad build.
• Silkscreen. Altium's DRC reports silkscreen-to-silkscreen and silkscreen-to-mask warnings. A few labels crowd each other near U1 and L1.
• What Adom Fields flagged in aiflow/fields.json:
  • three connectors (J2, J5, J7) carry GND off the board, so cables that meet off the board would close a ground loop;
  • two board edges have no ground via within 4.6 mm;
  • VIN, EN and VOUT have no protection diodes.

Parts

Every part has its own page on the Adom wiki, with its symbol, footprint and 3D model. The BOM with every distributor number is design/bom.csv. The inductor's 3D model was rebuilt on its page during this build: the vendor model's print and terminals clipped through its body.

part	qty	refs	value	what it does	source
TPS54202DDCR Texas Instruments	1	U1	TPS54202DDCR	sync buck 4.5-28 V 2 A 500 kHz	Mouser 595-TPS54202DDCR
AMPLH5030S-150MT Abracon	1	L1	15uH	output inductor	Mouser 815-AMPLH5030S-150T
EEE-FK1V470P Panasonic	1	C1	47uF 35V	input bulk (cable damping)	Mouser 667-EEE-FK1V470P
CC1206KKX7R8BB106 Yageo	2	C2, C3	10uF 25V X7R	input ceramic	Mouser 603-CC126KKX7R8BB106
0603B104J500CT Walsin	2	C4, C5	100nF 50V X7R	VIN pin HF bypass	Adom stock
CL21A226MPQNNNE Samsung	3	C6, C7, C8	22uF 10V X5R	output ceramic	Adom stock
0402N680J500CT Walsin	1	C9	68pF C0G	feed-forward across Rtop	Adom stock
CR0402-FX-6802GLF Bourns	1	R1	68k	FB top (series part 1)	Adom stock
CR0402-FX-5601GLF Bourns	1	R2	5.6k	FB top (series part 2)	Adom stock
CR0402-FX-1002GLF Bourns	3	R3, R7, R8	10k	FB bottom	Adom stock
CR0402-FX-1004GLF Bourns	1	R4	1M	EN UVLO top	Adom stock
CR0402-FX-1503GLF Bourns	1	R5	150k	EN UVLO bottom	Adom stock
CR0402-FX-2201GLF Bourns	1	R6	2.2k	LED resistor	Adom stock
IN-S63BTG Inolux	1	D1	green LED	5 V power-good indicator	Adom stock
MachineContactMedium Adom	7	J1 to J7	MachineContactMedium	molecule contact (VIN)	Adom stock
MachinePinMediumShort Adom	4	MP1 to MP4	MachinePinMediumShort	molecule machine pin (GND)	Adom stock
Test point pads board copper, no part	9	TP1 to TP9	-	probe pads on SW, FB, VOUT, GND, EN, VIN and VMON	on the board

What is in this repo