IBUF_INTERMDISABLE - IBUF_INTERMDISABLE - 2026.1 English - Primitive: Input Buffer With Input Buffer Disable and On-die Input Termination Disable

Primitive: Input Buffer With Input Buffer Disable and On-die Input Termination Disable

PRIMITIVE_GROUP: I/O
PRIMITIVE_SUBGROUP: INPUT_BUFFER

Introduction

The IBUF_INTERMDISABLE primitive is available in the HD I/O banks and is similar to the IBUF_IBUFDISABLE primitive in that it has a IBUFDISABLE port that can be used to disable the input buffer during periods that the buffer is not being used. The USE_IBUFDISABLE attribute must be set to TRUE and SIM_DEVICE to the appropriate value for this primitive to have the expected behavior specific to the architecture. The IBUF_INTERMDISABLE primitive also has an INTERMDISABLE port that can be used to disable the optional on-die receiver termination feature.

The IBUF_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. The IBUF_INTERMDISABLE primitive further allows the termination legs to be disabled whenever the INTERMDISABLE signal is asserted High. These features can be combined to reduce power whenever the input is idle. Input buffers that use the VREF power rail (such as SSTL and HSTL) benefit the most from the IBUFDISABLE signal being set to TRUE because they tend to have higher static power consumption than the non-VREF standards such as LVCMOS and LVTTL.

I/O attributes that do not impact the logic function of the component, such as IOSTANDARD and IBUF_LOW_PWR, should be supplied to the top-level port via an appropriate property.

Port Descriptions

Port	Direction	Width	Function
I	Input	1	Input port connection. Connect directly to top-level port in the design.
IBUFDISABLE	Input	1	Disables input path through the buffer and forces to a logic Low. This feature is generally used to reduce power at times when the I/O is idle for a period of time.
INTERMDISABLE	Input	1	Control to enable/disable of on-chip input termination. This is generally used to reduce power in long periods of an idle state.
O	Output	1	Buffer output representing the input path to the device.

Design Entry Method

Instantiation	Yes
Inference	No
IP and IP Integrator Catalog	No

Available Attributes

Attribute	Type	Allowed Values	Default	Description
SIM_DEVICE	STRING		"7SERIES"	Set the device version for simulation functionality.
USE_IBUFDISABLE	STRING	"TRUE", "FALSE", "T_CONTROL"	"TRUE"	Set this attribute to "TRUE" to enable the IBUFDISABLE pin.

VHDL Instantiation Template

Unless they already exist, copy the following two statements and paste them before the entity declaration.

Library UNISIM;
use UNISIM.vcomponents.all;


-- IBUF_INTERMDISABLE: Single-ended Input Buffer with Termination Input Disable
--                     May only be placed in High Range (HR) Banks
--                     7 Series
-- Xilinx HDL Language Template, version 2026.1

IBUF_INTERMDISABLE_inst : IBUF_INTERMDISABLE
generic map (
   IBUF_LOW_PWR => "TRUE", -- Low power (TRUE) vs. performance (FALSE) setting for referenced I/O standards
   IOSTANDARD => "DEFAULT", -- Specify the input I/O standard
   USE_IBUFDISABLE => "TRUE") -- Set to "TRUE" to enable IBUFDISABLE feature
port map (
   O => O,     -- Buffer output
   I => I,     -- Buffer input (connect directly to top-level port)
   INTERMDISABLE => INTERMDISABLE, -- Input Termination Disable
   IBUFDISABLE => IBUFDISABLE -- Buffer disable input, low=disable
);

-- End of IBUF_INTERMDISABLE_inst instantiation

Verilog Instantiation Template


// IBUF_INTERMDISABLE: Single-ended Input Buffer with Termination Input Disable
//                     May only be placed in High Range (HR) Banks
//                     7 Series
// Xilinx HDL Language Template, version 2026.1

IBUF_INTERMDISABLE #(
   .IBUF_LOW_PWR("TRUE"),   // Low power ("TRUE") vs. performance ("FALSE") for referenced I/O standards
   .IOSTANDARD("DEFAULT"),  // Specify the input I/O standard
   .USE_IBUFDISABLE("TRUE") // Set to "TRUE" to enable IBUFDISABLE feature
) IBUF_INTERMDISABLE_inst (
   .O(O),                    // Buffer output
   .I(I),                    // Buffer input (connect directly to top-level port)
   .IBUFDISABLE(IBUFDISABLE),    // Buffer disable input, high=disable
   .INTERMDISABLE(INTERMDISABLE) // Input Termination Disable
);

// End of IBUF_INTERMDISABLE_inst instantiation

Related Information

7 Series FPGAs SelectIO Resources User Guide (UG471)

IBUF_INTERMDISABLE - IBUF_INTERMDISABLE - 2026.1 English - Primitive: Input Buffer With Input Buffer Disable and On-die Input Termination Disable - UG953