Voltage drop on output pin to 3.217 V

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PDOS

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I am driving an opto-coupler (6N136) from pin 22, configured as output, on a Teensy 4.0. The opto-coupler in turn drives a relay.

Pin 22 on the Teensy 4 is connected via a 284 ohm resistor to the input pin (2) of the 6N136. The power supply to the Teensy is 3.40 V.

There is a voltage drop of 1.82 V across the 284 ohm output resistor, meaning pin 22 is supplying 6.41 mA. But the output voltage on pin 22 has dropped to 3.217 V. This surprised me, considering that it is only supplying 6.4 mA current.

Is this voltage drop on the output pin normal? Should I be concerned?

Peter.

In case someone asks why I am using a high speed opto-coupler to drive a mere relay, I needed one in a hurry and that was all I had to hand.
 
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