Optocoupler collector-emitter leakage

[gus789]

Hi,

I am trying to use the circuit in the diagram to a generate 0-10V dimmer signal for a LED driver. The input is a PWM signal from an arduino (0-5V). The problem is that the voltage at the output only goes down to 2.56V minimum. The datasheet for this coupler http://www.mouser.com/ds/2/427/tcet1100-240288.pdf says the max collector emitter cut off current is 100nA, which should translate to a negligible drop across the 12kOhm when the coupler is off. Am I missing something obvious or is there something wrong with the circuit?

Thanks!

[mij59]

Check the collector and emitter connections, they could be reversed.
 

[Seekonk]

Something is wrong.  I use this circuit as a quick and dirty high side FET driver at my camp with a 300K resistor and there is no noticeable leakage.