Electronics > Beginners

Choosing USB isolator, alternate option

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sairfan1:
I bought a cheap USB isolator from Aliexpress.

I was using Arduino Duo with Reprap RAMPS 1.6 module when i increase the voltage to 24v, the voltage regulator installed on Arduino Duo gave magic smoke, luckily everything else was safe including my computer.

But after all this my USB isolator stopped working, when I plug it in the computer it start getting hot, any idea, what  i can do to save it or its just gone?
I attached the picture of my existing one, can somebody tell me what is the dip switch is for?

I also want to know some well known USB isolator? (while staying on lower price)

OR can i use some serial voltage level convertor like in this post


Renate:
I'm not sure which regulator the arduino uses, but...
The 78XX series has a limit of 35 V input, but that's really only for the higher output voltage units.
Theoretically a 7805 should be able to tolerate 24 V, but why try.

Do you really need USB isolation?
Maybe you should isolate somewhere else at a lower data speed.
For instance (yes, I know, not your use case) if you are using USB for a serial connection, isolate the serial, not the USB.
For your multiaxis thing, some stepper drivers have isolated inputs.

sairfan1:
What is that dip switch on if for??
Does anyone know the reliable USB isolator

Gyro:
All of these isolators use Analog Devices  ADUM3160  or ADUM4160 isolator ICs. It's worth downloading the datasheet to understand them, the pin functions are very simple. The switch will be there to select the slew rate to match USB low speed or high full speed (the opto is there to mirror the same setting on the other side).

Each side of the isolator is separately powered to maintain isolation. You don't say what part of the isolator is getting hot, but it sounds as if it got back-driven with greater than 5V when your Duo smoked.

As for which ones are reliable - they all use a variant of the ADUM datasheet app circuit, so there's probably little to choose between them (apart from maybe DC-DC converter wattage). Once you look at the datasheet, it is very easy to see what features are implemented on any particular isolator from the product photo. There's not really much that affects 'reliability' so, within reason, the cheaper the better if you're likely to fry one.

On the up-side, the isolator almost certainly saved your PC USB port from damage. They are a good idea on the bench when it's possible to use them (anything that doesn't demand 480Mbps USB2 High speed).

magic:

--- Quote from: Gyro on September 01, 2021, 06:06:45 pm ---All of these isolators use Analog Devices  ADUM3160  or ADUM4160 isolator ICs.

--- End quote ---
Hmm, given the lack of markings on the chip I wonder if there is a chance that they don't.

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