the input diode cant take more than 40mA...
so u should limit it to 20mA...
u can use a resistor for that: (Vcc-1.7V)/(20mA)
e. g: Vcc=5V: (5V-1.7V)/(20mA) = appr. 165R
the output current should be far below 25mA...
u could use an internal arduino IO pin pull-up resistor for that (it is somewhere between 18kR and 50kR):
pinMode(inputPin, INPUT); digitalWrite(inputPin, HIGH);
take care to get the polarities right... 
A and C is +... IIRC