SSTL15, SSTL135, SSTL12, DIFF_SSTL15, DIFF_SSTL135, DIFF_SSTL12

Parallel end-termination resistors (commonly 50 Ω ) 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 = Z ₀ ) to the V _CCO /2. Untuned on-die source termination feature (OUTPUT_IMPEDANCE) provides the option of 40 Ω , 48 W, or 60 Ω of driver impedance in HP I/O banks. The driver output impedance is set to a default of 40 Ω . The differential (DIFF_) versions use complementary single-ended drivers for outputs, and differential receivers for inputs.