Device Architecture
Global Buffers with No Programmable Delays
The CLKBUF and CLKBUF_LVPECL/LVDS macros are composite macros that include an I/O macro
driving a global buffer, hardwired together (Figure 2-20).
The CLKINT macro provides a global buffer function driven by the FPGA core.
The CLKBUF, CLKBUF_LVPECL/LVDS, and CLKINT macros are pass-through clock sources and do not
use the PLL or provide any programmable delay functionality.
Many specific CLKBUF macros support the wide variety of single-ended and differential I/O
standards supported by Fusion devices. The available CLKBUF macros are described in the Fusion,
IGLOO/e and ProASIC3/E Macro Library Guide.
Clock Source
CLKBUF Macro
PAD
Clock Conditioning
Output
GLA
or
CLKBUF_LVDS/LVPECL Macro
PADN
CLKINT Macro
None
GLB
or
Y
Y
A
Y
PADP
GLC
Figure 2-20 • Global Buffers with No Programmable Delay
2-26
Preliminary v1.7
ACTEL [ Actel Corporation ]
