2 layers40 × 20 mm
2 layers14 × 11 mm
Micro bec
leshow/open_BECBEC 6-30V into 5V/9V for quads
- Size
- 14 × 11 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 13
- Nets
- 7
- Pads
- 32
- Tracks, vias
- 83, 11
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 2 Nov 2026
- Updated
- 6 Nov 2026
Overview
Micro bec is an open-source printed circuit board by leshow, from the leshow/open_BEC repository on GitHub. It is a 2-layer board of 14 × 11 mm with 13 parts on 7 nets, routed with 83 tracks and 11 vias.
Its parts include 6 capacitors, 3 resistors, 1 IC, 1 connector and 1 inductor.
README
README.mdmicro_bec
A small step-down BEC, copied matek micro BEC 6-30V as best I could
- Input: 6-30V (2-6S)
- Output: 5V by default, 9V with JP1 bridged (9V needs 3S or more)
- Current: 1.5A continuous, 2.5A peak
- Size: about 14 x 10mm, one 4-pin 2.54mm header
Circuit
TI LMR51430YFDDCR synchronous buck (4.5-36V in, 3A, 1.1MHz, forced PWM), TSOT-23-6.
| Part | Value |
|---|---|
| Input caps | 2x 4.7uF 50V |
| Bootstrap cap | 100nF, CB to SW |
| Inductor | 4.7uH, Isat 4.5A |
| Output caps | 2x 22uF 25V 0805 |
| Feedback | 100k top, 13.7k bottom, 15k + JP1 to GND for 9V |
Output voltage is 0.6V x (1 + 100k / R):
- JP1 open: R = 13.7k, ~4.98V
- JP1 bridged: R = 13.7k || 15k, ~8.98V
Pinout
| Pin | Net |
|---|---|
| 1 (square pad) | VIN |
| 2 | GND |
| 3 | GND |
| 4 | VOUT |
Libraries
The inductor footprint is in libs.pretty, pulled from LCSC with easyeda2kicad.
Add it as a footprint library named mp2315 with path ${KIPRJMOD}/libs.pretty
(Preferences > Manage Footprint Libraries > Project Specific Libraries).
Parts
13| Qty | Value | Footprint | References |
|---|---|---|---|
| 2 | 100nF 50V | Capacitor_SMD:C_0402_1005Metric | C3, C4 |
| 2 | 22uF 25V | Capacitor_SMD:C_0805_2012Metric | C5, C6 |
| 2 | 4.7uF 50V | Capacitor_SMD:C_1206_3216Metric | C1, C2 |
| 1 | 100k | Resistor_SMD:R_0402_1005Metric | R3 |
| 1 | 13.7k | Resistor_SMD:R_0402_1005Metric | R1 |
| 1 | 15k | Resistor_SMD:R_0402_1005Metric | R2 |
| 1 | 4.7uH | Inductor_SMD:L_Changjiang_FTC303018D | L1 |
| 1 | Conn_01x04_Pin | Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical | J1 |
| 1 | LMR51430YFDDCR | Package_TO_SOT_SMD:TSOT-23-6 | U1 |
| 1 | SolderJumper_2_Open | Jumper:SolderJumper-2_P1.3mm_Open_Pad1.0x1.5mm | JP1 |
Questions
How big is the Micro bec PCB?
It measures 14 × 11 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Micro bec use?
13 parts. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Micro bec KiCad files?
From the leshow/open_BEC repository on GitHub, at the commit this page was made from: the board is micro_bec.kicad_pcb and its schematic micro_bec.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Micro bec design in my own project?
Its repository states no licence, so its author keeps all rights: ask leshow before reusing the design.
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