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6N137 Opto-Coupler internal parts

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TripACT

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Hi all,

I'm trying to understand how this particular opto-coupler works internally.
Unfortunately i have not found any sufficient useful description on the way the internal section works.

6N137.PNG

I'll be glad if someone could elaborate on the way the photodiode works in the way it is connected according to the scheme i attached.

Thanks in advance,

Gary
 

Dear Gray
Hi
What do you want to know , exactly ? it is a simple opto coupler ( fast opto coupler ) . it has an LED internally , and a transistor ( internally ) . if you supply the LED , the transistor will be on . what is your further question ? about semiconductor inside it ?
Best Wishes
Goldsmith
 
hi goldsmith,

i know the general idea of it. yes - i'm trying to understand the semiconductor inside it. i'm trying to understand how the photodiode works in that connection..what would be the voltage drop when light is emitted from the LED and how the hell should it work if the diode is in reversed bias while to the cathode vcc is supplied. how the LED light affect the photodiode's voltage anyways..
and what is that gate before the AND gate...

you know... :)

Thanks,

Gary
 

how the hell should it work if the diode is in reversed bias while to the cathode vcc is supplied
Did you notice that most standard optocouplers, either photo-diode or photo-transistor type, are using a reversed biased junction as photo detector? That's far from being specfic to 6N137 "digital" opto couplers. You may want to read some basic literature about photo diodes.

6N137 is adding a kind of high speed amplifier/comparator. If designing the function as a discrete circuit, we would usually refer to a transimpedance amplifier (TIA) with a succeding comparator. 6N137 is a rather old device, so we expect can that it's made in a classical planar IC process, similar to the technology used for TTL and LS-TTL logic.
 
okay... i think i have a better perception now.

thank you.
 

thank you mister_rf :)

useful info. i did read those wiki pages 30 minutes ago.

i'll meet you on my other following questions regarding the IR2110 driver schematics (theory only), but that will be on a new topic obviously.

Gary
 

As a side remark, because the original post was asking about internal operation of 6N137, do we actually know the details?

I assumed a bipolar process, mister_rf expected a CMOS buffer. Most 6N137 datasheets (the device is available from different manufacturers) are explicitely describing a schottky clamped NPN output transistor, only Vishay says to use NMOS. According to input current and thresholds, the enable input is apparently a TTL-like bipolar logic input. Preamplifier technology isn't said, so we are effectively guessing.
 
FvM,

i think your description tells the exact story. I did check the datasheets and found about the use of NMOS as well by vishay.
Some manufacture's datasheets shows no discrete amplifier nor photodiode in reveresed bias but instead a NPN output transistor.
I guess they all must operate the same as they are tagged '6N137' component.
Funny enough, although Vishay describes the use of NMOS, their Capture/PSPice modules shows a general use of a NPN transistor.
In my simulations, the 6N137 Module supplied by Vishay acts as inverter because it consists an open-collector output transistor.
This seems to be expected from all the information i read and i guess all the '6N137' optocouplers work that way.
Connecting a pull-up configuration with an NPN inverts the logic pulse again and seems to solve this, to be in phase with the input.
 

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