I would like to use one of my extra SDRAM bank pins to drive some LEDS. I was thinking about using a mosfet, but considering that I'm only looking at driving a LED, it seemed like a bit much.
So what about this? If I configure the FPGA pin to be open drain, then will this work? I did do a search around here but there isn't anything about this particular configuration. LED forward voltage is 2V typ 2V5 max. Led load current is 6mA.
Here is my backup MOSFET cct, but considering it's a 0.5W device, it seems like overkill for this particular application.
Mosfet on threshold voltage is 0.7V typ and 1V max, ID is 1A when VDS is 1v5, so I think that the 1V8 should turn the mosfet on enough. It looks like the resistance is ~1.5ohm, so it's definitely on enough at VDS is 1V8.
Which is better? Is there a reason why I should go with the mosfet, even if it's a higher-power device?