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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 10th Feb 2023, 8:08 pm   #1
John_BS
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Default Dual opto-isolators: any experts?

I've just bought a few NOS HP opto-isolators HCPL-2531.

There is no spec in the data-sheet indicating
a) how closely matched the two halves might be, and
b) the maximum safe voltage allowed between the two LED's
Of the six samples I measured, the current transfer balance was generally within 15% .

I've decided to linearise the current transfer using a bridge feedback topology on the outputs, with the second opto providing the feedback element. However this might require two devices to avoid having 'hot' and 'cold' halves of the circuit on adjacent diodes!?

John
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File Type: pdf HCPL2530.PDF (210.2 KB, 33 views)
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Old 10th Feb 2023, 8:33 pm   #2
duncanlowe
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Default Re: Dual opto-isolators: any experts?

Not an expert at all. But aren't these a digital device? So linearity isn't going to be something considered? I've only ever used them in digital switching scenarios.
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Old 10th Feb 2023, 8:53 pm   #3
John_BS
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Default Re: Dual opto-isolators: any experts?

They can be used as switches, but they are sort of linear as well.
See page 7
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Old 10th Feb 2023, 9:13 pm   #4
Trigon.
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Default Re: Dual opto-isolators: any experts?

Quote:
Originally Posted by John_BS View Post
I've decided to linearise the current transfer using a bridge feedback topology on the outputs, with the second opto providing the feedback element.
I wonder if using this type of device might be easier?
IL300.pdf

Cheers
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Old 11th Feb 2023, 12:10 am   #5
DrStrangelove
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Default Re: Dual opto-isolators: any experts?

Leakage between the inputs is measured at 500V according to the datasheet if I'm reading it correctly.
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Old 11th Feb 2023, 3:56 pm   #6
John_BS
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Default Re: Dual opto-isolators: any experts?

Thanks guys: if I have a problem I'l try the IL300, but it looks like the diodes are not on the same substrate, so should be OK.
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