Add 5V DC/DC Converter (2S battery)

[slintak]

Add Power Supply Based on 2S Li-Ion Battery (6.0–8.4 V)

This pull request replaces the earlier power supply proposal (see #1) based on an incorrect 1S battery assumption.
The updated design expects a 2S Li-Ion/Li-Po battery, with a voltage range of 6.0 V to 8.4 V.

Summary of Changes

• Added a 5V step-down DC/DC converter based on a TPS562203.
• Expected voltage input range is 6.0 - 8.4 V. Expected voltage output is 5 V ± 3.3%.
• Efficiency around 96 % for 1 A output current, switching frequency 553 kHz.

Power Supply Details

• Input: 2S Li-Ion battery (6.0 V – 8.4 V)
• Output: 5.0 V @ 1.A (5 W)

Component	Voltage	Power [W]	Notes	Datasheet
MCM-iMX93	3.45–5.5 V	2.5	SoM. 3.3 V output should power only SD card.	PDF
SX1255IWLTRT	2.7–3.6 V	0.297	RF Transceiver	PDF
BGS12P2L6	1.65–3.4 V	0.000363	RF Switch	PDF
TAC5111	3.0–3.6 V	0.05973	Audio Codec	PDF
MAX9814	2.7–5.5 V	0.0198	Mic Preamp	PDF
ST7735R-based LCD	3.3 V est.	0.33	Estimated	—
Total	—	3.21 W	Max current draw from 5 V ≈ 0.65 A

The TPS562203 met all design requirements:

• Supports the full 2S Li-Ion voltage range (6.0–8.4 V)
• Provides enough power for our application (2 A max vs. 0.65 A expected)
• Offers excellent light-load efficiency (>90% at 10 mA)
• Readily available and well-supported (LCSC: C22445511)

Next Steps

• Circuit for switching between USB-C voltage (when connected) and battery voltage. This will be part of next PR.
• 3.3 V Power Rail: The MCM-iMX93 SoM provides a 3.3 V LDO output intended specifically for the SD card. A 3.3 V DC/DC converted has to be added.
• Charging Circuitry: As the battery is now 2S, a proper charging solution is not yet included in this PR.

Notes

• This PR supersedes the earlier power_supply in Add 5V DC/DC Converter and 1S Li-Ion Battery Charger #1, which has been closed.
• Open for review, feedback, and suggested modifications.

[sp5wwp]

Thanks! I'm worried about the size of the proposed inductor. It's 4.8mm high and that might be too much.