If the current-sinking PWM driver you like has open-collector (or open-drain) outputs you can use pull-up resistors (to 5V) to turn those output into 5V logic outputs. When the output is off the pull-up resistor will take the signal HIGH. When the output is on it will pull the signal LOW.
Do you have a datasheet or link to that CCR2 device? Most constant current driver devices have active outputs and would not work the way you are attempting to PWM it.Lefty