18W Wireless Charging Receiver Module 5W 15W for 3.7V 7.4V Lithium Battery DIY Fast Charging PCBA

High-power reception: Peak 18 W (12 V/1.5 A) under Qi EPP protocol, backward compatible with 5 W/7.5 W/10 W. Charges a 4500 mAh phone to 55% in 30 minutes, performance equivalent to 18 W wired QC2.0. Battery: 1-cell 3.7 V or 2-cell 7.4 V Li-ion battery, 2000–5000 mAh. Finished size similar to a lighter, ideal for TWS earbud cases, flashlights, handheld gimbals, and promotional gifts. | Chip      | Function                  | Package   | Features                                          | Price (CNY) | |-----------|---------------------------|-----------|---------------------------------------------------|-------------| | RX635     | Rectifier + EPP Decoding  | QFN-32    | Built-in 30 V synchronous rectifier, 92% efficiency | 4.8         | | IP2320/IP2325 | Linear Charge Management | ESOP-8    | 1–2 A adjustable, 4.2 V/8.4 V selectable           | 1.2         | | SW2303    | Buck-Boost Charging       | QFN-20    | 2 A direct charging, 93% efficiency                | 2.5         | Conclusion: For minimal BOM, choose RX635 + IP2320 linear solution. For 2 A high current or 2-cell 7.4 V batteries, choose RX635 + SW2303 buck-boost solution. 30 mm single coil, 0.5 mm × 105 strands Litz wire, DC resistance 65 mΩ, Q ≥ 80 @ 127 kHz. Resonance: 2 × 100 nF/50 V NPO capacitors, temperature drift ±30 ppm. RX635 integrates 30 V/15 mΩ full-bridge synchronous rectifier, supporting 5 V/9 V/12 V PDO. Built-in 12-bit voltage sampling, compatible with Qi EPP envelope detection, bit error rate < 0.1%. SW2303 with 1 µH alloy inductor, 2 A / 1 MHz switching frequency. Automatically steps down 12 V to 4.2 V/8.4 V with 93% efficiency. Supports 4-stage charging: trickle → CC → CV → recharge. Cutoff current at C/10. Input 30 V TVS surge protection. NTC thermal control: power reduction at 60 ℃, shutdown at 70 ℃. Battery protection: overcharge 4.3 V/8.6 V, over-discharge 2.7 V/5.4 V, over-current 3 A, short-circuit 0 V. Compliant with IEC62133. Red/green open-drain LEDs: ON during charging, OFF when full, 1 Hz flash on fault. I²C interface reserved for monitoring VRECT, IBAT, temperature, and secondary development. | Item                  | Specification                              | Remarks                                  | |-----------------------|--------------------------------------------|------------------------------------------| | Receiving Distance    | ≤ 5 mm                                     | Case thickness ≤ 2 mm                    | | Output PDO            | 5 V/2 A, 9 V/2 A, 12 V/1.5 A               | Auto-negotiates highest level            | | Battery Charging      | 4.2 V±1 %/2 A or 8.4 V±1 %/1.5 A           | 1-cell / 2-cell selectable               | | Peak Efficiency       | 92% × 93% ≈ 85%                            | 12 V → 8.4 V/1.5 A                       | | Standby Power         | 5 mW                                       | Battery leakage current 1 µA              | | Coil Temperature Rise | ≤ 15 ℃                                     | 25 ℃ ambient, 18 W full load             | | PCB Size              | 25 mm × 30 mm × 1.0 mm                     | 2-layer, single-sided SMT                | Coil: 30 mm diameter, 12 µH±10 %, Q ≥ 80 @ 127 kHz; 0.5 mm×105 strands Litz wire to reduce skin effect. Resonance Cap: 100 nF/50 V NPO, 2 parallel, drift ±30 ppm, capacity decay < 1% at 360 kHz. Rectifier Layout: RX635 full bridge within 5 mm of coil; Kelvin differential sensing to reduce spikes. Buck-Boost Inductor: 1 µH/4 A alloy, Isat ≥ 5 A, DCR < 20 mΩ, 3×3 mm package. Thermal Design: 0.3 mm graphite sheet + thermal pad on coil back; metal housing reduces temp by 5 ℃. EMI: 127–360 kHz frequency dithering ±5%, meets CISPR25 Class 3 without common-mode choke. Certification: Qi2 ready; 0.2 mm safety clearance, 2 oz copper for VRECT traces.