2.8.4.1 CLKBUF and HCLKBUF

CLKBUF (HCLKBUF) is used to drive a CLK (HCLK) from external pads. These macros can be used either generically or with the specific I/O standard desired (for example, CLKBUF_LVCMOS25, HCLKBUF_LVDS, and so on). See the following figure.

Figure 2-43. CLKBUF and HCLKBUF

Package pins CLKEP and CLKEN are associated with CLKE, package pins HCLKAP and HCLKAN are associated with HCLKA, and so on.

Note that when CLKBUF (HCLKBUF) is used with a single-ended I/O standard, it must be tied to the P-pad of the CLK (HCLK) package pin. In this case, the CLK (HCLK) N-pad can be used for user signals.