2 layers103 × 30.5 mm
2 layers30.5 × 12.1 mm
TTLSerialOptoisolator
cellularmitosis/TTLSerialOptoisolatorA board which provides isolation for a TTL serial TX / RX pair.
- Size
- 30.5 × 12.1 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 9
- Nets
- 10
- Pads
- 24
- Tracks, vias
- 46, 0
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 3
- Created
- 11 Apr 2015
- Updated
- 11 Apr 2015
Overview
TTLSerialOptoisolator is an open-source printed circuit board by cellularmitosis, from the cellularmitosis/TTLSerialOptoisolator repository on GitHub, published under the MIT licence. It is a 2-layer board of 30.5 × 12.1 mm with 9 parts on 10 nets, routed with 46 tracks and 0 vias.
Its parts include 4 resistors, 2 ICs and 2 connectors. It belongs with the interfaces and adapters boards of this library.
README
README.mdTTLSerialOptoisolator
A board which provides isolation for a TTL serial TX / RX pair.
License
This board design is Open-Source Hardware. It is licensed under the MIT License. It was designed by Jason Pepas.
Board design v1
Initial board design.
Gerbers
Schematic
PDF.
Design notes
LED series resistor calculation
Can we find an LED resistor value which works for both 3.3V and 5V TTL levels?
Lite-On LTV-817 datasheet: http://media.digikey.com/pdf/Data%20Sheets/Lite-On%20PDFs/LTV-817_827_847%28M,S,S_TA1%29.pdf
The forward voltage of the LED is typically 1.2V.
- 5V - 1.2V = 3.8V
- 3.3V - 1.2V = 2.1V
| Voltage | 100Ω | 150Ω | 220Ω | 330Ω | 470Ω | 680Ω | 1kΩ |
|---|---|---|---|---|---|---|---|
| 5V | 38mA | 25mA | 17mA | 12mA | 8mA | 6mA | 4mA |
| 3.3V | 21mA | 14mA | 10mA | 6mA | 4mA | 3mA | 2mA |
So 330Ω would be a reasonable choice.
Parts
9| Qty | Value | Footprint | References |
|---|---|---|---|
| 2 | 330 | R_AXIAL_0W25_059A_PL | R1, R4 |
| 2 | 4.7k | R_AXIAL_0W25_059A_PL | R2, R3 |
| 2 | 817C | DIP4_059A_PL | U1, U2 |
| 2 | CONN_4 | PIN_ARRAY_4x1 | P1, P2 |
| 1 | OSHW-logo_silkscreen-back_2mm | OSHW-logo_silkscreen-back_2mm | G*** |
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Questions
How big is the TTLSerialOptoisolator PCB?
It measures 30.5 × 12.1 mm and has 2 copper layers, 1.6 mm thick.
What parts does the TTLSerialOptoisolator use?
9 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 TTLSerialOptoisolator KiCad files?
From the cellularmitosis/TTLSerialOptoisolator repository on GitHub, at the commit this page was made from: the board is kicad/TTLSerialOptoisolator.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the TTLSerialOptoisolator design in my own project?
Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).