Hi everyone,
I'm working on a project that requires an optical isolator (Avago tech's ACSL-6210) that protects my circuit from a potential voltage swing ranging from 2.5 to 5 volts. I've been able to send signals out along the optoisolator from my PIC microcontroller (the Tx line) and have them recognized as valid signals, but am unable to receive signals (Rx) back through the isolator.
Since I needed a steady current value(between 7 and 15 mA) back through the isolator to turn it on, I placed an N-channel FET between the Rx line and the isolator, allowing the the signal to trigger the gate of the FET and pass a known voltage through a resistor to the opto. That worked for a little while, but then failed. I replaced the FET, but couldn't achieve the original results again.
I've also tried a P-Channel FET, but am not confident that it is being biased properly. Does anyone have any suggestions about how to get the FET's to work - or possibly an alternative configuration that will work too? I'll attach my schematic.
I'm working on a project that requires an optical isolator (Avago tech's ACSL-6210) that protects my circuit from a potential voltage swing ranging from 2.5 to 5 volts. I've been able to send signals out along the optoisolator from my PIC microcontroller (the Tx line) and have them recognized as valid signals, but am unable to receive signals (Rx) back through the isolator.
Since I needed a steady current value(between 7 and 15 mA) back through the isolator to turn it on, I placed an N-channel FET between the Rx line and the isolator, allowing the the signal to trigger the gate of the FET and pass a known voltage through a resistor to the opto. That worked for a little while, but then failed. I replaced the FET, but couldn't achieve the original results again.
I've also tried a P-Channel FET, but am not confident that it is being biased properly. Does anyone have any suggestions about how to get the FET's to work - or possibly an alternative configuration that will work too? I'll attach my schematic.