SSTL18_II, SSTL15_R, SSTL135_R, DIFF_SSTL18_II, DIFF_SSTL15_R, DIFF_SSTL135_R

Parallel end-termination resistors (commonly 50W) to V_TT = (V_CCO/2) are typically placed on the board close to any receiver. Depending on the board topology, source-termination series resistors help match the output driver impedance to the transmission line and end-termination impedances, to reduce reflections and improve signal integrity. Optional untuned split input ODT provides Thevenin equivalent resistance of R (where R = Z₀) to the V_CCO/2. The differential (DIFF_) versions use complementary single-ended drivers for outputs, and differential receivers for inputs.