I am using spartan3 fpga with lvcmos33 output pin set to 16 mA drive strength and fast slew rate. I am assuming that 16 mA is the source current at 3.3V as my VCCO voltage is 3.3V. I would like to know what is the sink current capability for LVCMOS33 OUTPUT pin is. Or is there any way I can increase the sink current capability?
I am using this output pin as open drain type with 150 Ohm pulllup to 1.8V Plane. With this I am seeing low swing of 400mV. If the sink current was truely
16 mA, then the low swing should have been 0v. I raised the pullup value to 330 Ohms and the low swing was 200mV.In my opinion the 16 mA is source current capability. I need to make the output go down to 0v.
Any help will be great.