Feb 3, 2014 #1 A alzomor Advanced Member level 2 Joined Jun 9, 2005 Messages 674 Helped 39 Reputation 78 Reaction score 8 Trophy points 1,298 Location Germany www.i-g.org Activity points 6,406 When I connect the PCF8575 outputs to the optocoupler through a 390 ohm resistor and drive the output high the output of the PCF8575 is 1V. Vf of the input led of the MOC3606 optocoupler is 1.2V , so the current sinked from the port is (5V-1.2)/390=9.74mA May you kindly tell me what is wrong with my calculations and design and how to solve the problem Attached you can find schematic for my circuit Regards Hossam Alzomor Attachments Schematic Prints.pdf 19.2 KB · Views: 75
When I connect the PCF8575 outputs to the optocoupler through a 390 ohm resistor and drive the output high the output of the PCF8575 is 1V. Vf of the input led of the MOC3606 optocoupler is 1.2V , so the current sinked from the port is (5V-1.2)/390=9.74mA May you kindly tell me what is wrong with my calculations and design and how to solve the problem Attached you can find schematic for my circuit Regards Hossam Alzomor