UltraScale Architecture SelectIO Resources User Guide (UG571)

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1.14 English

The IOBUFDS_INTERMDISABLE primitive (shown in This Figure) is available in the HR I/O banks. It has an IBUFDISABLE port that can be used to disable the input buffer during periods when the buffer is not being used. The IOBUFDS_INTERMDISABLE primitive also has an INTERMDISABLE port that can be used to disable the optional on-die receiver termination feature. See Uncalibrated Input Termination in I/O Banks for more details on this feature.

Figure 1-38:      Differential Bidirectional Buffer with Input Buffer Disable and On-Die Input Termination Disable (IOBUFDS_INTERMDISABLE)

X-Ref Target - Figure 1-38


The IOBUFDS_INTERMDISABLE primitive can disable the input buffer and force the O output to the internal logic to a logic-Low when the IBUFDISABLE signal is asserted High and the output buffer is 3-stated (T = High). The USE_IBUFDISABLE attribute must be set to TRUE, the IBUFDISABLE port must be controlled, and SIM_DEVICE set to ULTRASCALE for this primitive to have the expected behavior that is specific to the UltraScale architecture. If the I/O is using the on-die receiver termination feature, this primitive disables the termination legs whenever the INTERMDISABLE signal is asserted High and the output buffer is 3-stated. When the output buffer is 3-stated (T = High), the input buffer and any on-die receiver termination are controlled by IBUFDISABLE and INTERMFIDISABLE, respectively. When the output buffer is not 3-stated (T = Low), the input buffer and on-die receiver termination are disabled and the O output (to the internal logic) is forced to a logic-Low. These features can be combined to reduce power whenever the input is idle for a period of time.

Although uncommon, if a design requires an input be constantly enabled while maintaining the ability to dynamically control DCI, this primitive can be used by floating the IBUFDISABLE pin and setting the USE_IBUFDISABLE attribute to FALSE.