#Goal

- Replace the AMS1117-3.3 linear regulator (U1) with an in-stock, 5V-to-3.3V, ≥1A synchronous buck converter and its supporting passive components to improve efficiency and reduce noise coupling into sensitive audio/ADC circuits in the AI Brick Phone 8dcd design.

#Implementation plan

1. Disable and remove the AMS1117-3.3 regulator (U1) from the schematic, breaking its VIN, VOUT, and GND nets while reserving its footprint area near the VCC input.

2. Select an in-stock synchronous buck converter component from the Flux parts library rated for a 5V input and 3.3V output at ≥1A. Confirm if a fixed or adjustable version is preferable based on component availability.

3. Add supporting components in accordance with the buck converter datasheet:

3.1. Place the datasheet-specified inductor with a ripple characteristic of 20–40% of full load current and a saturation current of at least 1.2× the peak load current.

3.2. Add high-quality ceramic input and output capacitors (voltage ratings ≥1.5×3.3V) to stabilize voltage and filter noise.

3.3. Implement the feedback resistor network if an adjustable buck converter is chosen.

4. Rewire connections: connect VIN to the USB 5V (VCC) input, VOUT to the +3V3 rail, and ensure the common ground is properly connected.

5. Layout the new buck converter stage with an emphasis on best practices:

5.1. Keep the high di/dt loop compact and use short, wide traces to reduce impedance and EMI.

5.2. Segregate and properly isolate the power converter ground from the analog ground used by sensitive audio/ADC circuits (NS4150B, ES7210/ES8311) to minimize interference.

5.3. Maintain the existing decoupling scheme on the +3V3 rail for critical loads.

6. Verify the design by running ERC/DRC checks and reviewing component availability in the parts library.

#Success criteria

- The AMS1117-3.3 is successfully replaced with a properly specified, in-stock synchronous buck converter delivering 3.3V at ≥1A.

- The buck converter and its supportive passive components are correctly placed, wired with short, low-impedance paths, and isolated from high-noise areas.

- ERC/DRC checks pass without errors and the design meets noise isolation requirements for audio/ADC circuits.