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MOC3021 drive small load directly?

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Hi. I'm trying to use an MOC3021 opto triac to control small load Rload =100 ohm , and Vin about = 6->12VAC, so can i drive the load directly ? , i have read datasheet note :"This optoisolator should not be used to drive a load directly"


Another question :
hinh.jpg
Both of schematic i use MCU,zero crossing voltage to control phase, Can i get only the negative cycle with the schematic above?
 

I've read the datasheet warning myself, but in the past I've also driven small loads directly from the optocoupler, as long as the load itself is completely resistive.

It is not a good design practice, so I would not recommend it for a commercial product.
 

Hi,

datasheet note :"This optoisolator should not be used to drive a load directly"
Click to expand...
So how can anyone of us recommend something in direct opposite to the datasheet?
The datasheet is as clear as can be in this question.

And in case someone recommends you to do it ... and it fails ... do you want to blame it on him?

--> It will always be your own risk if you refuse to follow the datasheet.

Klaus
 

schmitt trigger said:
I've read the datasheet warning myself, but in the past I've also driven small loads directly from the optocoupler, as long as the load itself is completely resistive.

It is not a good design practice, so I would not recommend it for a commercial product.
Click to expand...

Thanks ! So how about the second schematic , can i get the negative cycle ?

- - - Updated - - -

KlausST said:
Hi,


So how can anyone of us recommend something in direct opposite to the datasheet?
The datasheet is as clear as can be in this question.

And in case someone recommends you to do it ... and it fails ... do you want to blame it on him?

--> It will always be your own risk if you refuse to follow the datasheet.

Klaus
Click to expand...

Ok i got it ! Thanks
 

Hi,

Why don't you use a photomos relay?

Klaus
 

Use a SCR instead of the Triac. The SCR conducts in one direction only, like a diode.
 

Max total Power Dissipation for optocoupler output is 300mw
if your load below this value, you are in safe zone and you can drive load directly
anyway, to use external triac or back to back scr is the best
 

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