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Contents

The video
Key specs
Molecule interface
Parts on the Adom wiki
Feature guides
What is in this repo

README

markdown

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

The buck molecule, KiCad 10 3D render: VIN, GND and EN contacts on the left, VOUT, GND and VMON on the right, four corner machine pins

A 12 V to 5 V, 1 A synchronous buck on the TI TPS54202, designed as a 28 x 20 mm Adom molecule.

It takes the brief from the YouTube video "Hardware Design with GPT-6: Schematic, PSpice & PCB" by Inside Embedded (12 V in, 5 V at 1 A out, terminals, test points) and designs it again from scratch. Every value comes from the datasheet equations. The loop and the switching behaviour were simulated in ngspice, and the result was checked against TI's own PSpice model. The board was placed, routed, poured and analysed in KiCad 10 with Adom AI Flow, and its copper was checked for current density and temperature with Adom Fields.

It was built with a set of Adom tools working together; here is the full list.

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

The video

About four minutes, start to finish: the prompt in Adom Hydrogen, the circuit, three SPICE engines in agreement, the live layout in KiCad 10, the current and heat analysis and the rework it caused, the silkscreen placed live, the part models and their wiki pages, and what it cost to build.

Watch on YouTube · How the video was made: capture, shots and scenes, so you can make one for your own board.

Key specs


input	12 V nominal, designed for 9 to 16 V; EN undervoltage lockout starts at 8.58 V and stops at 6.87 V
output	5 V (4.98 V nominal from stocked divider values), 1 A continuous
controller	TI TPS54202DDCR, 500 kHz synchronous buck, internal compensation, SOT-23-6
inductor	15 uH Abracon AMPLH5030S-150MT (Isat 3.7 A)
output capacitance	3 x 22 uF X5R, 36.3 uF effective at 5 V
loop (ngspice, 12 V, 1 A)	28.6 kHz crossover, 110 deg phase margin with 68 pF Cff
output ripple (ngspice, 12 V, 1 A)	3.2 mV peak to peak
load step (TI PSpice model)	about 185 mV (3.7 %) for a 1 A step
efficiency (estimate)	93 % at 12 V, 1 A
current density (Adom Fields)	50 A/mm2 peak, at the SW node beside U1
thermal (Adom Fields, still air)	U1 +45 C at its GND pin, L1 +41 C; 55 C junction-based budget
board	28 x 20 mm, 2 layers, 0.5 oz copper, 4 medium machine pins on a 24 x 16 mm grid, 6 contacts, 4 probe pads
DRC (KiCad 10.0.5)	0 errors, 0 unconnected
sourcing	Mouser plus Adom stocked basic parts, for a 3rd party fab

Molecule interface

28 x 20 mm, 2 layers. Positions are in mm from MP1. The molecule's GLB, STEP, footprint and symbol JSON are in molecule/; the KiCad 10 project is in kicad/.

contact	position	net	notes
J1	(0, 12)	VIN	9 to 16 V, 12 V nominal; UVLO starts at 8.58 V, stops at 6.87 V
J2	(0, 8)	GND	input return
J3	(0, 4)	EN	open drain low turns it off; released, the UVLO divider decides
J4	(24, 12)	VOUT	4.98 V, 1 A
J5	(24, 8)	GND	output and signal ground
J6	(24, 4)	VMON	VOUT / 2 (2.49 V) for a 3.3 V ADC, 5 k source
MP1 to MP4	(0, 0), (24, 0), (0, 16), (24, 16)	GND	medium machine pins

Probe pads: TP1 SW (15.6, 4.9), TP2 FB (9.4, 5.6), TP3 VOUT (21.6, 4.9), TP4 GND (15.6, 2.8).

Parts on the Adom wiki

Every part on this board has its own page on the Adom wiki, with its symbol, footprint and 3D model, ready to reuse in your own designs.

ref	part	page
U1	TI TPS54202DDCR buck regulator	TPS54202DDCR
L1	15 uH inductor, Abracon	AMPLH5030S-150MT
C1	47 uF 35 V electrolytic, Panasonic	EEE-FK1V470P
C2, C3	10 uF 25 V X7R 1206, Yageo	CC1206KKX7R8BB106
C4, C5	100 nF 50 V X7R 0603, Walsin	0603B104J500CT
C6, C7, C8	22 uF 10 V X5R 0805, Samsung	CL21A226MPQNNNE
C9	68 pF C0G 0402, Walsin	0402N680J500CT
R1	68 k 0402, Bourns	CR0402-FX-6802GLF
R2	5.6 k 0402, Bourns	CR0402-FX-5601GLF
R3, R7, R8	10 k 0402, Bourns	CR0402-FX-1002GLF
R4	1 M 0402, Bourns	CR0402-FX-1004GLF
R5	150 k 0402, Bourns	CR0402-FX-1503GLF
R6	2.2 k 0402, Bourns	CR0402-FX-2201GLF
D1	green LED 0603, Inolux	IN-S63BTG
MP1 to MP4	medium machine pin, Adom	MachinePinMediumShort
J1 to J6	medium machine contact, Adom	MachineContactMedium

Feature guides

guide	what it covers
The Adom tools	Every Adom tool used on this board, what each one did, and a link to its page.
Circuit design	The brief, why the TPS54202, and every calculation: inductor (15 uH vs Lmin), COUT, the 68 pF Cff, the stocked-value divider search, EN UVLO, bootstrap, losses.
Simulation	ngspice loop gain across Cff, the switching transient at 9, 12 and 16 V, and the check against TI's PSpice model.
Sourcing	The BOM with Mouser part numbers, the 3rd party fab sourcing policy, and where every 3D model came from.
Board	Molecule format, design rules, placement, routing, pours with the SW patch, DRC, copper and silkscreen.
Thermal and current	Adom Fields current density (SW peak 50 A/mm2), where the heat goes, and the still-air budget.
How the video was made	Capturing the footage while the board is built, the shots and scenes, and putting the video together.
Build clips	Watch the board being built in KiCad: placement, routing, pours, the analyses and the silkscreen.

What is in this repo

folder	contents
`design/`	`calcs.py` (every datasheet equation, run it to regenerate `calcs.json`) and `bom.csv`
`sim/`	the ngspice loop and switching models with their results and plots, and the TI PSpice comparison
`kicad/`	KiCad 10 project: schematic, board, design rules, the netlist the board was generated from, the generator scripts, project libraries and every 3D model
`aiflow/spec.json`	the layout constraints the board was built to: wide nets, Kelvin taps, loads, hot parts, pours and the thermal budget
`molecule/`	the molecule STEP (KiCad 10 export), the anchored GLB and the footprint and symbol JSON