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| Element | XC3000 | XC4000E | XC4000X | XC5200 | XC9000 | Spartan | SpartanXL | Spartan2 | Virtex |
|---|---|---|---|---|---|---|---|---|---|
| IBUF | Primitive | Primitive | Primitive | Primitive | Primitive | Primitive | Primitive | Primitive | Primitive |
| IBUF4, IBUF8, IBUF16 | Macro | Macro | Macro | Macro | Macro | Macro | Macro | Macro | Macro |
IBUF, IBUF4, IBUF8, and IBUF16 are single- and multiple-input buffers. An IBUF isolates the internal circuit from the signals coming into a chip. IBUFs are contained in input/output blocks (IOBs). IBUF inputs (I) are connected to an IPAD or an IOPAD. IBUF outputs (O) are connected to the internal circuit.
For Virtex and Spartan2, refer to the “IBUF_selectIO” section for information on IBUF variants with selectable I/O interfaces. IBUF, 4, 8, and 16 use the LVTTL standard.
Figure 6.3 IBUF8 Implementation XC3000, XC4000E, XC4000X, XC5200, XC9000, Spartan, SpartanXL, Spartan2, Virtex