2 layers
2 layers43.2 × 31.8 mm
Low voltage
oliverpaddock/OpenMicAn open source audio interface
- Size
- 43.2 × 31.8 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 23
- Nets
- 14
- Pads
- 78
- Tracks, vias
- 89, 58
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 8 Apr 2025
- Updated
- 25 Sep 2026
Overview
Low voltage is an open-source printed circuit board by oliverpaddock, from the oliverpaddock/OpenMic repository on GitHub, published under the CERN-OHL-S-2.0 licence. It is a 2-layer board of 43.2 × 31.8 mm with 23 parts on 14 nets, routed with 89 tracks and 58 vias.
It is built around the TPS62171DSG, TPS62172DSG and 0805W8F1003T5E (SMT业务专用), with the CL21A106KAYNNNE, CL21B105KBFNNNE and ANR3015T2R2M among its other parts. Its parts include 6 capacitors, 6 resistors, 3 ICs, 2 connectors and 2 inductors.
Main components
7
TPS62171DSG
WSON-8-EP(2x2)-40℃~+85℃@(TA) 1 1.8V 17uA 2.25MHz 3V~17V 500mA Buck Buck Built-in Fixed Yes WSON-8-EP(2x2) DC-DC Converters ROHSTexas InstrumentsDC-DC ConvertersTPS62172DSG
WSON-8-EP(2x2)-40℃~+85℃@(TA) 1 17uA 2.25MHz 3.3V 3V~17V 500mA Buck Built-in Fixed Overcurrent Protection、Light load efficient mode、Operating status indication Step-down type Yes WSON-8-EP(2x2) DC-DC Converters ROHSTexas InstrumentsDC-DC Converters
0805W8F1003T5E (SMT业务专用)
0805100kΩ ±1% 0805 Chip Resistor - Surface Mount ROHSUNI-ROYALChip Resistor - Surface Mount
CL21A106KAYNNNE
080510uF 25V X5R ±10% 0805 Multilayer Ceramic Capacitors MLCC - SMD/SMT ROHSSamsung Electro-MechanicsMultilayer Ceramic Capacitors MLCC - SMD/SMTCL21B105KBFNNNE
08051uF 50V X7R ±10% 0805 Multilayer Ceramic Capacitors MLCC - SMD/SMT ROHSSamsung Electro-MechanicsMultilayer Ceramic Capacitors MLCC - SMD/SMT
ANR3015T2R2M
SMD,3x3mm2.2uH 2A 2A Magnetic Shielded Inductor ±20% SMD,3x3mm Power Inductors ROHSAPVPower InductorsCL21A226MAQNNNE
080522uF 25V X5R ±20% 0805 Multilayer Ceramic Capacitors MLCC - SMD/SMT ROHSSamsung Electro-MechanicsMultilayer Ceramic Capacitors MLCC - SMD/SMT
README
README.mdOpenMic
OpenMic is an open-source, 2-in, 2-out, usb-c audio interface.
About
Why open source?
Open source audio/music hardware is not scarce, but general-purpose open source audio interfaces for musicians are essentially non-existent. OpenMic brings repairability, transparency, and education to an overlooked corner of music hardware.
You own your hardware. All schematics, firmware, and design files are publicly accessible so you can repair it, modify it, and understand it.
What is OpenMic?
If you aren't familiar with audio interfaces like the Focusrite Scarlett 2i2 or the Universal Audio Apollo Twin, they basically take analog audio - from a microphone, a guitar, a synth, etc. - and convert it into digital audio your computer can use in a DAW like Ableton, Logic, or Audacity. They also convert digital audio from your computer back into analog audio that you can hear through speakers or headphones. Interfaces also typically provide some sort of amplification or volume control on the inputs and outputs.
This is exactly what OpenMic does. Two inputs that can take microphone/line/instrument level signals, outputs for your speakers, and a headphone jack. Plus a few other features like phantom power that are listed in more detail in the Features section.
System block diagram
Current Status
OpenMic is currently in the prototyping stage. The circuit has been designed and simulated, and individual systems are being built and tested. View the schematics to see the current circuit design.
Progress will be posted on the OpenMic blog as prototyping continues.
Roadmap
- Initial design and component selection
- Simulation for design verification
- Subsystem prototyping
- Full board design in KiCad
- First full v1 board
- Crowd supply launch
- Production
Features
- 2 combo XLR/TRS inputs (mic/line/inst)
- Balanced TRS stereo line outputs
- TRS headphone output
- 48V phantom power
- Direct monitoring
- Up to 32-bit/96kHz
- USB-C bus powered (1.5A) with external USB-C fallback
- Drives headphones from 32Ω to 600Ω
- Fully open hardware and firmware
Getting Started
If you want to view/edit KiCAD files, make sure to add the part libraries located in /hardware/libs to your project or globally in your KiCAD instance.
Sponsors
Special Thanks
THAT Corporation
Neutrik
Parts
23| Qty | Value | Footprint | References |
|---|---|---|---|
| 5 | 100k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R1, R2, R5, R6, R9 |
| 2 | 10uF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C2, C3 |
| 2 | 1uF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C11, C14 |
| 2 | 2.2uH | Inductor_SMD_Wurth:L_Wurth_WE-LQSH-3012 | L2, L3 |
| 2 | 22uF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C6, C7 |
| 1 | 470 | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R7 |
| 1 | Conn_01x02_Pin | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | J3 |
| 1 | Conn_01x07_Pin | Connector_PinHeader_2.54mm:PinHeader_1x07_P2.54mm_Vertical | J4 |
| 1 | EN_0V9 | Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm | JP3 |
| 1 | EN_1V8 | Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm | JP2 |
| 1 | EN_3V | Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm | JP1 |
| 1 | LED | LED_SMD:LED_0805_2012Metric_Pad1.15x1.40mm_HandSolder | D1 |
| 1 | TPS62171DSG | Package_SON:WSON-8-1EP_2x2mm_P0.5mm_EP0.9x1.6mm_ThermalVias | U2 |
| 1 | TPS62172DSG | Package_SON:WSON-8-1EP_2x2mm_P0.5mm_EP0.9x1.6mm_ThermalVias | U1 |
| 1 | TPS7A2009 | Package_TO_SOT_SMD:SOT-23-5 | U5 |
Questions
How big is the Low voltage PCB?
It measures 43.2 × 31.8 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Low voltage use?
23 parts, built around the TPS62171DSG, TPS62172DSG, 0805W8F1003T5E (SMT业务专用) and CL21A106KAYNNNE. 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 Low voltage KiCad files?
From the oliverpaddock/OpenMic repository on GitHub, at the commit this page was made from: the board is hardware/pcb/prototypes/power/v2-3v/low-voltage.kicad_pcb and its schematic hardware/pcb/main-board/codec.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Low voltage design in my own project?
Its repository publishes it under the CERN-OHL-S-2.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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