Primitive: Differential Input/Output Buffer
- PRIMITIVE_GROUP: I/O
- PRIMITIVE_SUBGROUP: BIDIR_BUFFER
- Families: UltraScale, UltraScale+
Introduction
The IOBUFDS is a differential input/output buffer primitive. 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.
Logic Table
| Inputs | Bidirectional | Outputs | ||
|---|---|---|---|---|
| I | T | IO | IOB | O |
| X | 1 | Z | Z | No Change |
| 0 | 0 | 0 | 1 | 0 |
| I | 0 | 1 | 0 | 1 |
Port Descriptions
| Port | Direction | Width | Function |
|---|---|---|---|
| I | Input | 1 | Input of OBUF. Connect to the logic driving the output port. |
| IO | Inout | 1 | Bidirectional diff_p port to be connected directly to top-level inout port. |
| IOB | Inout | 1 | Bidirectional diff_n 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 | No |
| IP and IP Integrator Catalog | No |