# BoostCore-Module **BoostCore-Module** is a compact adjustable DC-DC step-up boost converter module built around the **MT3608** regulator. It supports **USB-C 5V input**, an optional **external VIN input**, Schottky OR-ing input selection, resettable fuse protection, TVS protection on USB VBUS, and a trimpot-adjustable output feedback network. > **PCB manufacturing sponsor:** This project is sponsored by **PCBWay**. > PCBWay support is mentioned in the documentation because the PCB is intended to be published as an open hardware project and manufactured as a compact prototype board. --- ## Project Highlights - MT3608 based boost converter - USB-C power-only input - External VIN input - Input OR-ing with SS36 Schottky diodes - USB-C VBUS protection with 5V TVS diode - USB-C PTC fuse protection - Optional VIN_EXT PTC fuse protection - Adjustable output voltage using trimpot - 0805 resistor/LED-friendly design choices - Test points for VIN, VOUT, FB, EN and GND - KiCad-ready hardware folder structure - GitHub documentation package with BOM, assembly, layout and testing guides --- ## Sponsorship This project is sponsored by **PCBWay**. PCBWay is mentioned here as the PCB manufacturing sponsor for the open hardware release of BoostCore-Module. The board was designed with prototype manufacturing in mind, including compact routing, silkscreen labels, test points, and an export-ready project structure. --- ## Electrical Overview | Parameter | Value | |---|---:| | Controller IC | MT3608 | | Topology | Boost / step-up | | USB-C input | 5V only | | External VIN input | 2V-24V target range | | Output voltage | Adjustable by RV1 trimpot | | Switching frequency | MT3608 typical 1.2MHz | | Inductor | 4.7uH recommended | | Main boost diode | SS36, 3A, 60V | | Output adjustment | R1 + R2 + RV1 feedback network | | Output capacitor caution | Use 50V capacitors for high output voltage | --- ## Current Feedback Network The adjustable output stage is: ```text VOUT -> R2 10k -> RV1 100k trimpot -> FB -> R1 2.2k -> GND ``` Recommended trimpot wiring: ```text RV1 pin 3 -> R2 side RV1 pin 1 + pin 2 -> FB node ``` Formula: ```text VOUT = 0.6 x (1 + R_UPPER / R1) ``` Where: ```text R_UPPER = R2 + active RV1 resistance R1 = 2.2k ``` Important: - Start with the trimpot at the lowest output setting. - Always adjust output using a multimeter. - Do not connect a sensitive load before confirming VOUT. - High output voltages require output capacitors rated above the selected voltage. --- ## Images ### Layout preview ![PCB layout](docs/images/BoostCore%20Module.png) ![PCB layout 1](docs/images/BoostCore%20Module_1.png) ![PCB layout 2](docs/images/BoostCore%20Module_2.png) --- ## Important Hardware Notes ### USB-C input The USB-C connector is used as a **5V power-only input**. Required CC resistors: ```text CC1 -> 5.1k -> GND CC2 -> 5.1k -> GND ``` USB-PD negotiation is not implemented. The USB-C input is therefore **5V only**. ### F1 USB fuse Current selected part: ```text F1 = KLM3S300RY PTC resettable fuse 1206 / 3A / 6V USB-C 5V input only ``` Do not use this part on the 24V external input path. ### F2 external VIN fuse Compact option: ```text F2 = MF-MSMF110/24X-2 1812 / 1.1A / 24V ``` Higher-current but larger option: ```text F2_ALT = FSMD185-2920-R 2920 / 1.85A / 33V ``` ### D2 USB TVS D2 must be a **5V TVS diode**, not a Schottky diode. Recommended: ```text D2 = P4SMAJ5.0_R1_00001 ``` ### D1 / D3 / D4 The board uses SS36 diodes: ```text D1 = SS36 D3 = SS36 D4 = SS36 ``` D3 and D4 are used for input OR-ing. ### C4 polarity If using the compact electrolytic output capacitor: ```text C4 (+) -> VOUT C4 (-) -> GND ``` Mark polarity clearly on silkscreen. --- ## PCB Layout Rules Boost converters are layout-sensitive. Follow these rules: 1. Keep the **SW node** as short and small as possible. 2. The SW node is: ```text U1 pin 1 SW + L1 right side + D1 anode ``` 3. Do not place copper pour under the SW node area. 4. Keep FB trace away from SW node, diode switching node and inductor. 5. Place C1 close to U1 IN and GND. 6. Place output capacitors close to D1 cathode and GND. 7. Use a solid GND plane on the bottom layer. 8. Add via stitching near high-current GND return paths. 9. Do not route feedback under the inductor. 10. Make VIN_SYS and VOUT traces wide. --- ## Assembly Order Recommended assembly sequence: 1. Inspect PCB visually. 2. Solder USB-C connector. 3. Solder protection parts: F1, D2, D3, D4. 4. Solder MT3608. 5. Solder inductor L1 and diode D1. 6. Solder resistors and small capacitors. 7. Solder RV1 trimpot. 8. Solder output capacitors. 9. Solder connectors. 10. Inspect polarity of C4. 11. Check shorts between VIN, VOUT and GND. 12. Power on without load. 13. Adjust output voltage with a multimeter. 14. Test with a dummy load. --- ## First Power-Up Checklist Before applying power: - Check USB-C VBUS is not shorted to GND. - Check VIN_SYS is not shorted to GND. - Check VOUT is not shorted to GND. - Confirm D1 cathode points to VOUT. - Confirm C4 polarity. - Confirm RV1 pin 1+2 go to FB. - Confirm RV1 pin 3 goes to R2. - Confirm EN is pulled to VIN_SYS through R6. Initial test: ```text 1. Apply input power. 2. Measure VIN_SYS. 3. Measure VOUT. 4. Adjust RV1 slowly. 5. Verify output under light load. 6. Check temperature of MT3608, L1 and D1. ``` --- ## License Released as open hardware documentation. See `LICENSE`. --- ## Disclaimer This is an open hardware project. Use at your own risk. Verify all footprints, ratings, clearances, capacitor voltage ratings and component stock before fabrication or ordering.