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| LED based optoisolator that can work from 5V 150uA 300Hz signal |
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| Psi:
I'm trying to help someone remotely and it would be much easer if I could point them to an optoisolator that will accept a 5V, 150uA input signal directly to the LED. Data freq is 300hz. As you would expect all the normal optos just don't get bright enough at 150uA to switch NPN hard enough to generate a good output, even with 500k pullup on a darlington opto. Digital optos would work, but the person doesn't have easy access to 5V to power it on the input side. With such high efficiency leds available today you would think there must be something that can handle low currents. I've seen led's that are pretty bright on 150uA Does such a thing exist? |
| wraper:
Say SFH608-5 should work IMHO. CTR is Rated at 0.5mA, so I guess it should still work at 0.15mA with significantly degraded CTR. There is also SFH618A-5 which has the same CTR specs, however it also has a graph showing that at 0.1mA it's still functional. |
| wraper:
LDA111 Darlington should work as well according to the graph. https://www.ixysic.com/home/pdfs.nsf/0/66F34A78811BAA3985256A2C00693C54/$file/Lda111.pdf |
| Zero999:
--- Quote from: Psi on November 22, 2020, 03:30:29 am ---I'm trying to help someone remotely and it would be much easer if I could point them to an optoisolator that will accept a 5V, 150uA input signal directly to the LED. Data freq is 300hz. As you would expect all the normal optos just don't get bright enough at 150uA to switch NPN hard enough to generate a good output, even with 500k pullup on a darlington opto. Digital optos would work, but the person doesn't have easy access to 5V to power it on the input side. With such high efficiency leds available today you would think there must be something that can handle low currents. I've seen led's that are pretty bright on 150uA Does such a thing exist? --- End quote --- How about a low current digital isolator, such as the ISO7021? https://www.ti.com/lit/ds/symlink/iso7021.pdf |
| Psi:
--- Quote from: Zero999 on November 22, 2020, 12:19:01 pm ---How about a low current digital isolator, such as the ISO7021? https://www.ti.com/lit/ds/symlink/iso7021.pdf --- End quote --- That would require a power connection on the input side, which is problematic. |
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