Open-source Buck-Boost DC/DC power module based on SC8703 chip, with input voltage up to 36V, input/output current up to 10A, switching frequency of 600kHz, adjustable output voltage, adjustable constant output current, maximum conversion efficiency of 95%, XT30 input/output connectors, Type-C port, supports PD fast charging input, capable of negotiating up to 28V.
Design Parameters
| Parameter | Value |
|---|---|
| Input Voltage Range | 2.7V ~ 36V |
| Output Voltage Range | 1.21V ~ 36V |
| Max Input/Output Current | 10A |
| Adjustable Constant Output Current Range | 0.58A ~ 10A |
| Switching Frequency | 600kHz |
| PCB Size | 79.6 x 47 mm |
The Buck-Boost power controller chip is SC8703, and the fast-charging protocol chip is CH224Q.
Replication Notes
- This project was designed using KiCAD. The project on LCSC’s Open Source Platform was imported from the KiCAD project file, so there might be minor issues. For replication, it is recommended to directly use the Gerber files I provided to order PCBs.
- The project is open-sourced on Gitee, LCSC Open Hardware Platform, and Huaqiu Open Hardware Community. Project materials and links to open-source platforms are available at the bottom of this article. Provided materials include: KiCAD project files, Gerber fabrication files, detailed BOM (with component purchase links and prices), combined top and bottom stencil file, silkscreen placement diagrams, interactive BOM (for soldering assistance), datasheets of used chips, PCBA and enclosure 3D models, etc.
- The enclosure is a ready-made aluminum alloy case purchased from Taobao. The purchase link is included in the BOM. The front and rear panels of the enclosure were 3D printed by myself; the 3MF model files are included in the provided materials.
- The MOSFETs must make thermal contact with the enclosure using thermal silicone pads!
- When operating without additional heatsinking, it is recommended to keep the working current below 5A!
- The Type-C input and XT30 input connectors are connected in parallel — do not use both simultaneously!
The component cost for small batches is approximately 30 RMB per set (excluding PCB and enclosure). The main cost driver is the SC8703 chip, which costs about 9 RMB per piece.
Project video demonstration: https://www.bilibili.com/video/BV1mMfPBzEXH/
QQ Group for Electronics/MCU Technical Discussion: 2169025065
eeClub - Electronic Engineers Community: https://bbs.eeclub.top/
Physical Photos
Soldering Process
Order a 10x10 cm stainless steel stencil from Taobao using the stencil file I provided (costs about 15 RMB). Then 3D print a solder paste applicator jig to securely align the stencil with the PCB. Apply solder paste, place components according to the interactive BOM, and then place the board on a heating plate or reflow oven. It is recommended to solder the bottom side first, then the top side.
Testing
Power-on test: 12V input, 24V output, no-load power consumption around 0.37W.
Type-C input test: Using a 65W PD charger, successfully negotiated 20V output.
Conversion Efficiency Test
Simple unboxing review of the Ruideng RD6012P digital programmable power supply: https://blog.zeruns.com/archives/740.html
Maximum measured conversion efficiency: 95.45%
| Input Voltage (V) | Input Current (A) | Input Power (W) | Output Voltage (V) | Output Current (A) | Output Power (W) | Efficiency (%) |
|---|---|---|---|---|---|---|
| 35.999 | 0.752 | 27.071 | 24.130 | 1.000 | 24.130 | 89.14% |
| 35.999 | 6.699 | 241.157 | 23.954 | 9.600 | 229.955 | 95.35% |
| 5.000 | 9.063 | 45.315 | 24.028 | 1.500 | 36.042 | 79.54% |
| 5.000 | 8.520 | 42.600 | 12.054 | 3.000 | 36.162 | 84.89% |
| 12.000 | 4.382 | 52.584 | 5.230 | 9.000 | 47.070 | 89.51% |
| 11.999 | 8.753 | 105.027 | 24.048 | 4.000 | 96.192 | 91.59% |
| 5.000 | 9.803 | 49.015 | 19.990 | 2.000 | 39.980 | 81.57% |
| 5.000 | 5.063 | 25.315 | 21.116 | 1.000 | 21.116 | 83.41% |
| 11.999 | 6.705 | 80.453 | 35.477 | 2.000 | 70.954 | 88.19% |
| 35.999 | 3.459 | 124.521 | 11.998 | 9.510 | 114.097 | 91.63% |
| 35.999 | 1.839 | 66.202 | 12.023 | 5.000 | 60.116 | 90.81% |
| 35.999 | 9.288 | 334.359 | 35.460 | 9.000 | 319.141 | 95.45% |
MOS Gate Drive Waveforms
Waveform of high-side MOSFET gate-to-ground on the input side (Buck section): switching frequency is 607kHz, period ~1.65μs, Miller plateau duration ~20ns — normal, clean waveform with no ringing and minimal overshoot.
Waveform of high-side MOSFET gate-to-ground on the output side (Boost section): switching frequency is 607kHz, period ~1.65μs. Overshoot and ringing occur during MOS turn-on, likely due to suboptimal gate drive routing.
Ripple Test
Simple unboxing review of the Rigol DHO914S oscilloscope: https://blog.zeruns.com/archives/764.html
With 12V input and 24V output at no load, measured ripple peak-to-peak is ~60mV.
With 12V input and 24V/2A output, measured ripple peak-to-peak is ~200mV.
With 24V input and 5V output at no load, measured ripple peak-to-peak is ~16mV.
With 24V input and 5V/2A output, measured ripple peak-to-peak is ~35mV.
Thermal Imaging
Without any heatsinking, when operating at 36V input and 24V/9.5A output, MOSFET temperature rises above 100°C within 5 seconds. Bottom-side thermal image shown below.
Front-side thermal image: SC8703 chip temperature exceeds 70°C.
Thermal image with aluminum enclosure installed. Due to reflectivity of aluminum affecting measurement accuracy, a piece of tape was applied to the center. The temperature at the MOSFET contact surface is measured at approximately 53°C.
Download Links
Materials provided include: KiCAD project files, Gerber fabrication files, detailed BOM (with component purchase links and prices), combined top and bottom stencil file, silkscreen placement diagrams, interactive BOM (for soldering assistance), datasheets of used chips, PCBA and enclosure 3D models, etc.
- Gitee: https://gitee.com/zeruns/sc8703_-buck-boost
- GitHub: https://github.com/zeruns/sc8703_-buck-boost
- LCSC Open Source: https://oshwhub.com/zeruns/sc8703_buck-boost
- Huaqiu Open Platform: https://p.eda.cn/d-1341729185952956416
- 123Yunpan (123 Cloud Disk): https://www.123865.com/s/2Y9Djv-I9ddH
Recommended Open-Source Projects
- Open-sourced a 3-phase power monitor for easy home energy usage tracking: https://blog.zeruns.com/archives/771.html
- Open-source STM32-based synchronous rectification Buck-Boost digital power supply: https://blog.zeruns.com/archives/791.html
- LM25118 automatic Buck-Boost adjustable DCDC power module: https://blog.zeruns.com/archives/727.html
- Open-source intelligent electronic load based on CH32V307, competition project: https://blog.zeruns.com/archives/785.html
- EG1151 high-power synchronous rectification Buck-Boost power module (supports Type-C PD fast charging input): https://blog.zeruns.com/archives/794.html
- Open-source 140W+65W Buck-Boost PD3.1 fast charging module (2C+1A ports), IP6557+IP6538, 205W desktop charger: https://blog.zeruns.com/archives/801.html
- Open-source Type-C dock with 4x 10Gbps USB-A ports, 2.5G Ethernet, and card reader: https://blog.zeruns.com/archives/868.html
- [Open-source] 24V3A flyback switch-mode power supply (based on UC3842, includes circuit and transformer parameter calculations): https://blog.zeruns.com/archives/910.html
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- Affordable and high-performance VPS/cloud server recommendations: https://blog.zeruns.com/archives/383.html
- Minecraft server setup guide: https://blog.zeruns.com/tag/mc/
- GL-RM1PE unboxing and teardown — enabling BMC remote management on regular PCs: https://blog.zeruns.com/archives/900.html
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- OWON HDS160 oscilloscope multimeter unboxing and teardown: https://blog.zeruns.com/archives/927.html
- One-click Minecraft server setup guide supporting all versions (Forge, Fabric, Paper, Bedrock, etc.): https://blog.zeruns.com/archives/923.html
