USB-C Port Implementation
- Use a CC-controller or dedicated USB-C port logic to set the correct Rp resistor on the CC line so that the upstream charger will source the desired current (e.g. 1.5 A or 3 A per USB-C spec). 〈Based on “implementing USB-C source port”〉
- Include the usual USB-C front-end protections:
- A small decoupling capacitor on VBUS (≥1 µF close to the connector)
- Pull-down resistors on both CC pins (to advertise Rd if you’re sinking, or Rp if sourcing)
- A bidirectional USB-C-rated TVS diode for ESD protection (capacitance < 1 pF per line) 〈Based on “USB Type-C projects” and “designing USB circuits”〉
Single-Cell Li-Ion Charger IC
- Select a switch-mode Li-Ion charger (not a linear LDO-style charger) that implements the CC/CV algorithm for a 3.7 V nominal (4.2 V full) cell. 〈Based on “designing single-cell li-ion battery charger”〉
- Look for charger ICs that:
- Accept a 5 V USB input up to 1.5 A (or higher if you negotiate PD)
- Provide high efficiency (≥ 90%) through synchronous buck regulation
- Integrate battery-protection and status outputs (CHG/STAT pins) for safety and user feedback 〈Based on “designing battery charger”〉