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using optocouplers with micro controller

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mshh

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i want optocoupler it's input is 5v that come from microcntroller and Vcc is also 5v.
 

alexan_e

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What is the problem you have?
You can connect the optocoupler diode directly (with a resistor of course ) if your mcu can provide the current that you need for the diode, if not you have to use a transistor to provide more current.
A higher current in the diode will give a higher current in the optocoupler transistor.

Alex
 

mshh

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does any optocoupler work with vcc 5v
 

alexan_e

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The optocoupler doesn't have a power supply, it has a diode in the input that can work will a voltage of 2v (Check Vf in the datasheet) or more and the output is a transistor that can be connected to any voltage and configuration assuming that you don't exceed the transistor max ratings (voltage, current, power)

Alex
 

Tahmid

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Hi,
You can use any standard opto-coupler. The input side of the opto-coupler is a LED. If you just limit the current flowing through to the LED, then you have no problem using it at 5v or (much) higher. The output side is the transistor. The maximum voltage that can be applied/connected to the transistor depends on which opto-coupler you are using. So, it's best to check the datasheet for that. You can find the datasheet from a site such as Datasheet catalog for integrated circuits, diodes, triacs, and other semiconductors, view . A few common opto-couples are 4N25, 4N35, MCT2E, PC817, TLP521, etc

Hope this helps.
Tahmid.
 

bohumilfulin

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My favourite for rs232 is PC900V with 1K resistor @5V. also works 6N137.
Max speed is 115200B tested.
 

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