IOBUFDS_DIFF_OUT_INTERMDISABLE - 2021.2 English

Vivado Design Suite 7 Series FPGA and Zynq-7000 SoC Libraries Guide (UG953)

Document ID
UG953
Release Date
2021-10-22
Version
2021.2 English

Primitive: Bi-Directional Differential Buffer with Input Termination Disable, Input Disable, and Differential Output

Introduction

This design element is a bidirectional differential I/O Buffer used to connect internal logic to an external bidirectional pin. This element includes an uncalibrated input termination (INTERM) disable as well as input path disable as additional power saving features when the I/O is either is an unused state or being used as an output for several clock cycles. The IOBUFDS_DIFF_OUT_INTERMDISABLE differs from the IOBUFDS_INTERMDISABLE in that it allows internal access to both phases of the differential signal. This element may only be placed in High Range (HR) banks in the 7 series devices.

Port Descriptions

Port Direction Width Function
IO In/out 1 Bi-directional p-side port connection. Connect directly to top-level port in the design.
IOB In/out 1 Bi-directional n-side port connection. Connect directly to top-level port in the design.
I Input 1 Buffer input representing the output path to the device.
IBUFDISABLE Input 1 Disables input path through the buffer and forces to a logic high when USE_IBUFDISABLE is set to "TRUE". If USE_IBUFDISABLE is set to "FALSE" this input is ignored and should be tied to ground. This feature is generally used to reduce power at times when the I/O is either idle or during sustained write (output) conditions.
INTERMDISABLE Input 1 Disables input termination. This feature is generally used to reduce power at times when the I/O is either idle or during sustained write (output) conditions.
TM Input 1 P-side or master side of the high impedance 3-state mode when the I/O is being used for a read (input) operation. The TM pin also affects the IBUFDISABLE function when USE_IBUFDISABLE = "TRUE", and disables INTERM when in a write (output) mode.
TS Input 1 N-side or slave side of the high impedance 3-state mode when the I/O is being used for a read (input) operation. The TS pin also affects the IBUFDISABLE function when USE_IBUFDISABLE = "TRUE", and disables INTERM when in a write (output) mode.
O Output 1 Buffer p-side output representing the input path to the device.
OB Output 1 Buffer n-side output representing the input path to the device.

Design Entry Method

Instantiation Yes
Inference No
IP Catalog Yes
Macro support No

Available Attributes

Attribute Type Allowed Values Default Description
DIFF_TERM STRING "TRUE", "FALSE" "FALSE" Turns the built-in differential termination on (TRUE) or off (FALSE).
IBUF_LOW_PWR STRING "TRUE", "FALSE" "TRUE" Allows a trade off of lower power consumption vs. highest performance when referenced I/O standards are used.
IOSTANDARD STRING See Data Sheet "DEFAULT" Assigns an I/O standard to the element.
USE_IBUFDISABLE STRING "TRUE", "FALSE" "TRUE" Enables or disables the feature of IBUFDISABLE. Generally used when it is not desirable to have the T pin disable input path to allow a read during write operation.

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;

-- IOBUFDS_DIFF_OUT_INTERMDISABLE:  Differential Global Clock Buffer with Differential Output
--                                  Input Termination and Input Path Disable
--                                  May only be placed in High Range (HR) Banks
--                                  7 Series
-- Xilinx HDL Language Template, version 2021.2

IOBUFDS_DIFF_OUT_INTERMDISABLE_inst : IOBUFDS_DIFF_OUT_INTERMDISABLE
generic map (
   DIFF_TERM => "FALSE", -- Differential Termination (TRUE/FALSE)
   IBUF_LOW_PWR => "TRUE", -- Low Power - TRUE, High Performance = FALSE
   IOSTANDARD => "BLVDS_25", -- Specify the I/O standard
   USE_IBUFDISABLE => "TRUE") -- Use IBUFDISABLE function, "TRUE" or "FALSE"
port map (
   O => O,     -- Buffer p-side output
   OB => OB,   -- Buffer n-side output
   IO => IO,   -- Diff_p inout (connect directly to top-level port)
   IOB => IOB, -- Diff_n inout (connect directly to top-level port)
   I => I,     -- Buffer input
   IBUFDISABLE => IBUFDISABLE, -- input disable input, high=disable
   INTERMDISABLE => INTERMDISABLE, -- Input termination disable input
   TM => TM,   -- 3-state enable input, high=input, low=output
   TS => TS    -- 3-state enable input, high=output, low=input
);

-- End of IOBUFDS_DIFF_OUT_INTERMDISABLE_inst instantiation

Verilog Instantiation Template


// IOBUFDS_DIFF_OUT_INTERMDISABLE: Differential Global Clock Buffer with Differential Output
//                                 Input Termination and Input Path Disable
//                                 May only be placed in High Range (HR) Banks
//                                 7 Series
// Xilinx HDL Language Template, version 2021.2

IOBUFDS_DIFF_OUT_INTERMDISABLE #(
   .DIFF_TERM("FALSE"),     // Differential Termination, "TRUE"/"FALSE"
   .IBUF_LOW_PWR("TRUE"),   // Low power="TRUE", Highest performance="FALSE"
   .IOSTANDARD("DEFAULT"),  // Specify the input I/O standard
   .USE_IBUFDISABLE("TRUE") // Set to "TRUE" to enable IBUFDISABLE feature
) IOBUFDS_DIFF_OUT_INTERMDISABLE_inst (
   .O(O),     // Buffer p-side output
   .OB(OB),   // Buffer n-side output
   .IO(IO),   // Diff_p inout (connect directly to top-level port)
   .IOB(IOB), // Diff_n inout (connect directly to top-level port)
   .I(I),     // Buffer input
   .INTERMDISABLE(INTERMDISABLE), //  Input termination disable input
   .IBUFDISABLE(IBUFDISABLE),     // Input disable input, high=disable
   .TM(TM),   // 3-state enable input, high=input, low=output
   .TS(TS)    // 3-state enable input, high=input, low=output
);

// End of IOBUFDS_DIFF_OUT_INTERMDISABLE_inst instantiation

Related Information

  • See the 7 Series FPGA SelectIO Resources User Guide (UG471).