Primitive: Input/Output Buffer
- PRIMITIVE_GROUP: I/O
- PRIMITIVE_SUBGROUP: BIDIR_BUFFER
- Families: UltraScale, UltraScale+
Introduction
The IOBUF primitive is needed when bidirectional signals require both an input buffer and a 3-state output buffer with an active-High 3-state T pin. The IOBUF is a generic IOBUF. A logic-High on the T pin disables the output buffer. When the output buffer is 3-stated (T = High), the input buffer and any on-die receiver termination (uncalibrated or DCI) are ON. When the output buffer is not 3-stated (T = Low), any on-die receiver termination (uncalibrated or DCI) is disabled.
I/O attributes that do not impact the logic function of the component such as IOSTANDARD, DRIVE and SLEW should be supplied to the top-level port via an appropriate property. For details on applying such properties to the associated port, see the Vivado Design Suite Properties Reference Guide (UG912).
Logic Table
| Inputs | Bidirectional | Outputs | |
|---|---|---|---|
| T | I | IO | O |
| 1 | X | Z | IO |
| 0 | 1 | 1 | 1 |
| 0 | 0 | 0 | 0 |
Port Descriptions
| Port | Direction | Width | Function |
|---|---|---|---|
| I | Input | 1 | Input of OBUF. Connect to the logic driving the output port. |
| IO | Inout | 1 | Bidirectional port to be connected directly to top-level inout port. |
| O | Output | 1 | Output path of the buffer. |
| T | Input | 1 | 3-state enable input signifying whether the buffer acts as an input or output. |
Design Entry Method
| Instantiation | Yes |
| Inference | Recommended |
| IP and IP Integrator Catalog | No |