Explore PC817 pins, signal names, electrical functions and connection guidance for each package.
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Positive terminal of the internal infrared emitter. Forward current produces the light that controls the output transistor.
Drive through a current-limiting resistor from the input circuit.
Select resistance from the input voltage and forward voltage; never connect directly across a voltage source.
Negative terminal of the infrared emitter.
Return to the input-side ground or input driver.
This is not internally connected to the output emitter or its ground.
Emitter of the isolated NPN phototransistor.
For the common-emitter example, return to the output-side ground.
There is no base pin. Light from the input emitter controls collector current.
Collector of the isolated NPN phototransistor.
Connect a pull-up resistor to the output-side supply; take the output signal from this node.
Light increases collector conduction and pulls the common-emitter output low. The output needs its own supply.
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