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| Element | XC3000 | XC4000E | XC4000X | XC5200 | XC9000 | Spartan | SpartanXL | Spartan2 | Virtex |
|---|---|---|---|---|---|---|---|---|---|
| OBUFE | Macro | Macro | Macro | Macro | Primitive | Macro | Macro | Macro | Macro |
| OBUFE4, OBUFE8, OBUFE16 | Macro | Macro | Macro | Macro | Macro | Macro | Macro | Macro | Macro |
OBUFE, OBUFE4, OBUFE8, and OBUFE16 are 3-state buffers with inputs I, I3 - I0, I7 - I0, and I15-I0, respectively; outputs O, O3 - O0, O7 - O0, and O15-O0, respectively; and active-High output enable (E). When E is High, data on the inputs of the buffers is transferred to the corresponding outputs. When E is Low, the output is High impedance (off or Z state). An OBUFE isolates the internal circuit and provides drive current for signals leaving a chip. An OBUFE output is connected to an OPAD or an IOPAD. An OBUFE input is connected to the internal circuit.
| Inputs | Outputs | |
|---|---|---|
| E | I | O |
| 0 | X | Z |
| 1 | 1 | 1 |
| 1 | 0 | 0 |
Figure 8.2 OBUFE Implementation XC3000, XC4000E, XC4000X, XC5200, Spartan, SpartanXL, Spartan2, VirtexFigure 8.3 OBUFE8 Implementation XC3000, XC4000E, XC4000X, XC5200, XC9000, Spartan, SpartanXL, Spartan2, Virtex