Electronics > Projects, Designs, and Technical Stuff

Driving an optocoupler LED at different supply voltages

<< < (5/9) > >>

Benta:

--- Quote from: Yansi on January 16, 2019, 08:34:52 pm ---Do you see on what part of text I have reacted? Do you get it?

--- End quote ---

Not really. You've presented a bipolar solution that doesn't really help the OP (far too large voltage drop). Then you've referred to "unobtainium" JFETs, as if it is important to present a current within +/-1% to an optocoupler. After that you lost me.

The JFET solution is not precise, but will work down to almost 0 V voltage drop.

BrianHG:
+1 On the JFet constant current solution.  It has a close to 0.0v drop.

Yansi:

--- Quote from: Benta on January 16, 2019, 08:43:46 pm ---
--- Quote from: Yansi on January 16, 2019, 08:34:52 pm ---Do you see on what part of text I have reacted? Do you get it?

--- End quote ---

Not really. You've presented a bipolar solution that doesn't really help the OP (far too large voltage drop). Then you've referred to "unobtainium" JFETs, as if it is important to present a current within +/-1% to an optocoupler. After that you lost me.

The JFET solution is not precise, but will work down to almost 0 V voltage drop.

--- End quote ---

And that is a reason to start attacking me? Wtf is wrong with you?

Interfacing (any) LED from a 1.8V logic direct is a bad idea anyway.

Benta:

--- Quote from: Yansi on January 16, 2019, 09:16:57 pm ---And that is a reason to start attacking me? Wtf is wrong with you?

--- End quote ---

I'm not attacking you. I've pointed out that your solution does not fulfill the requirements of the OP. That's all.

SiliconWizard:
Not sure you'll find a simple current source design with only 100mV dropout (in the least favorable case)...

What's your budget exactly (you want something cheap?), and how many digital signals do you actually have to isolate? Only one or several?
For an alternative solution, you could have a look at this: https://www.maximintegrated.com/en/products/interface/isolation/MAX14930.html

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod