Timeline for MAX485 Receive Output pin current sufficient for optocoupler LED?
Current License: CC BY-SA 4.0
8 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Sep 25, 2018 at 11:04 | vote | accept | J. Doe | ||
| Sep 24, 2018 at 10:33 | comment | added | Spehro 'speff' Pefhany | @J.Doe Definitely more conservative. It depends on your requirements. Your nominal LED design current is a trade-off of course. Either too high or too low is bad. For hobby purposes I think the published circuit is probably okay. If I was making 1000+ I would look more closely. | |
| Sep 24, 2018 at 3:31 | comment | added | J. Doe | so its better to use a buffer that can sink more current, like 20mA, that will also help after led has aged, correct ? | |
| Sep 24, 2018 at 3:24 | comment | added | Spehro 'speff' Pefhany | @J.Doe The LED will require more current to emit the same amount of light as it ages. Vds is across the internal N-channel MOSFET at the driver output (drain to source, of course). | |
| Sep 24, 2018 at 3:20 | comment | added | J. Doe | aging of led ? optocoupler stops working after too much use ? also where is Vds ? | |
| Sep 23, 2018 at 16:59 | history | edited | Spehro 'speff' Pefhany | CC BY-SA 4.0 |
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| Sep 23, 2018 at 16:46 | history | edited | Spehro 'speff' Pefhany | CC BY-SA 4.0 |
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| Sep 23, 2018 at 16:33 | history | answered | Spehro 'speff' Pefhany | CC BY-SA 4.0 |