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Electronics design & layout Two independent DC–DC channels (buck or synchronous) with constant-current (CC) control and optional PWM modulation (10–20 kHz). Input: 5 V DC (USB-C PD source), total current up to 3 A. Output per channel: adjustable 2.5–4.0 V / 0.5–2.5 A, continuous mode. Integrated current sensing and thermal protection logic. Control & sensors Microcontroller to manage both channels, modes (Eco / Normal / Boost), and read sensors. Integration with temperature / humidity sensor (e.g. SHTC3 or similar, I²C). Optional NTC input for hot-side monitoring and overheat cutoff. Auto-off trigger from accelerometer or motion sensor (shoe movement simulation). Power and protection USB-C PD trigger module (fixed 5 V or 9 V profile). Reverse-polarity, over-current, and over-temperature protection. Optional PTC fuse or MOSFET ideal diode on main input. Mechanical & integration constraints Total PCB thickness ≤ 2 mm. Target area per board ≈ 25 × 40 mm. Connectors: JST-SH / GH or flexible flat cable (FPC) compatible. Operates in thermally variable and partially flexible environment (inside soft enclosure). Firmware tasks Closed-loop current control with adjustable limits per mode. Reading sensors and computing dew-point-based threshold logic (T_cold ≥ T_dew + 1 °C). Power-saving standby and automatic shutdown conditions. Optional direction control (H-bridge / polarity switch). Prototype & validation Provide schematic, PCB Gerber files, BOM, and basic firmware (C/Arduino or equivalent). Target efficiency over 85 % per channel at 1 A. Deliver one assembled prototype or verified PCB for lab testing.