6N136 output from emitter - Page 1
Forum section: electronics / beginners

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: June 02, 2018, 07:15:59 am
content: The datasheet shows pin 5 as ground and most of the reference circuits that I have seen only use the collector output of the 6N136 with a pullup connected to pin 6 (collector pin).I have a case where I need to use the emitter as output so can I take the output from emitter like the given circuit.So can I use the6N1376N136 in this mode?

author: Zero999
author_rank: Super Contributor
timestamp: June 02, 2018, 08:17:38 am
content: Yes, it makes no difference whether the output is taken from the emitter or collector.

author: Andy Watson
author_rank: Super Contributor
timestamp: June 02, 2018, 08:32:15 am
content: Your title says 6N136 but you asked about 6N137 - I would say that the latter needs a power supply for its logic.

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: June 02, 2018, 08:37:11 am
content: That was a typo. this question was purely related to the 6N136.

author: glarsson
author_rank: Frequent Contributor
timestamp: June 02, 2018, 08:52:56 am
content: Quote from: Hero999 on June 02, 2018, 08:17:38 amWhat about the screen thing connected to the gnu/emitter pin? What problems will the screen cause when it is connected to the signal output instead of ground?

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: June 02, 2018, 09:20:00 am
content: Quote from: Andy Watson on June 02, 2018, 08:32:15 amI also see that the 6N136 has a Vcc pin what is that used for if there is no logic inside the 6N136, can I operate the 6N136 without giving supply to that Vcc pin.

author: digsys
author_rank: Unknown
timestamp: June 02, 2018, 10:01:07 am
content: www.mouser.com/ds/2/149/6n135-288701.pdfIt's not yournormalopto-coupler. High speed, high immunity etc. Similar to logic drive optos. There are heaps ofstandardoptos ie 4n35 etcif this part is not suitable. ie you only need isolation

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: June 02, 2018, 10:34:42 am
content: Quote from: digsys on June 02, 2018, 10:01:07 amMy requirement is high speed, that's why I chose this part, my original question still remains, whether I can use this part with emitter as an output. I'm aware that I could use another transistor stage after this part and solve my problem, but if this part can do it all by itself then I would not need extra parts.

author: Ian.M
author_rank: Super Contributor
timestamp: June 02, 2018, 11:09:33 am
content: From the datasheet:QuoteIf you wire the bias connection to the transistor collector it will be much much slower due to the Miller effect - the negative feedback from collector to base via the photodiode's junction capacitance. It will probably be slower than an ordinary slow optocoupler as it hasn't been optimised to operate in that configuration.The only way to regain *some* of its speed would be if you had a supply rail a lot higher than the logic supply to provide the Vcc bias, then you could connect the collector to the logic supply. It would still be a lot slower because the photocurrent would have to discharge and the base current charge the photodiode's junction capacitance through the full output voltage swing range.

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: June 02, 2018, 11:57:17 am
content: Quote from: Ian.M on June 02, 2018, 11:09:33 amI gather by what you are sayng that although it is possible to use the emitter output of the 6N35 it will be slower than a general purpose optocoupler.Is there an high speed alternative of 4N35 that I don't need to use VCC etc. just plain old transistor output so I can use it in the configuration given in the first post.

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: June 02, 2018, 12:21:26 pm
content: So how about connecting a PNP at the output of the 6N136 like so

author: digsys
author_rank: Unknown
timestamp: June 02, 2018, 01:08:17 pm
content: If you're after high speed, with controlled jitter, on/off slope specs, I've always gone with logic output types ie SFH67xx seriesNo other parts required, but do need a supply voltage. What you suggest is perfectly ok as well, but a logic output type has dynamic drive both H / L

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: June 02, 2018, 03:42:57 pm
content: Quote from: digsys on June 02, 2018, 01:08:17 pmSFH6702 showing EOL on mouser

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 02, 2018, 10:16:10 pm
content: No. Emitter incurs Miller effect through the photodiode, making it little or no better than a 4N35.FYI, if you need high dV/dt, consider SFH6345. 6N136 isembarrassinglybad at dV/dt.Tim