Which optoisolators?

[rogueeve575]

Thanks for this! So I have a FM80, inverter, hub, and (not yet installed) FNDC on a 48V system with LifePO4 and I'm considering using your project to replace the MATE for remote monitoring purposes so I can check on how the system is doing when not there. I can't find in any of the documentation which optoisolators you used for the physical interface. It would be nice to have a list of which components people have had success with to save some time scrolling through DigiKey searches.

[jorticus]

Honestly I've forgotten what optoisolators I've used, but they don't need to be terribly special, as long as it satisfies the following specs:

Switching Frequency: ~10kHz (9600 baud), or ton/toff < 50us
Voltage: 24V (VCE >= 24V)
CTR doesn't matter (just need logic level conversion)

Sort by lowest price, in stock, and orderable in single quantities presents these as possible candidates on Mouser:

• Wurth 140817140310 (VCE = 35V, f = 80kHz, Vf = 1.4V, If = 60mA)
• Toshiba TLP293 (VCE = 80V, f = 20-80kHz, Vf = 1.4V, If = 50mA)
• Onsemi FOD81x series (VCE = 70V, f=80kHz, Vf = 1.4V, If = 50mA)
• Vishay VO618A (VCE = 80V, f = 100kHz, Vf = 1.65V, If = 60mA)

Then choose the resistors using Vf & If. Probably around 1kohm is appropriate.

I can't guarantee these will work, but they seem to have the right specs.

See this schematic for how the MATE connects to the bus (left side):
https://cdn.hackaday.io/images/766401441957799536.png