I'm looking to drive a bank of eight FOD4216 random phase triac drivers. I'm looking specifically at the (insanely expensive, $3!) Fairchild FOD4218, which needs 1.3mA to switch. 8 * 1.3 = 10.4 mA total draw for the bank of 8.
My uC can only sink/source 5mA, so I need some way to drive my optocouplers. I'd prefer to keep as low powered as possible, but a focus on minimizing the number of components leads my concerns. Somehow I need to get my uC from sourcing the whole 1.3 mA per optocoupler, down to sourcing no more than .625mA (5mA/8units = .625/unit) of the 1.3mA drive. Some headroom past that for the uC would be good. What would be good ways to create these 8 optocoupler drivers?
Not sure if it's helpful in doing the maths here, but forward voltage drop in the emitter appears to be between 0.9 - 1.2V across the full range of temperatures.