Global Resources in Actel Low-Power Flash Devices
v1.1
3 - 11
Use these available macros to assign a signal to the global network. In addition to these global
macros, PLL and CLKDLY macros can also drive the global networks. Use I/O–standard–specific clock
macros (CLKBUF_x) to instantiate a specific I/O standard for the global signals.
Table 3-7 shows the
list of these I/O–standard–specific macros. Note that if you use these I/O–standard–specific clock
macros, you cannot change the I/O standard later in the design stage. If you use the regular
CLKBUF macro, you can use MVN or the PDC file in Designer to change the I/O standard. The
default I/O standard for CLKBUF is LVTTL in the current Actel Libero Integrated Design
Environment (IDE) and Designer software.
Table 3-6
Clock Macros
Macro Name
Description
Symbol
CLKBUF
Input macro for Clock Network
CLKBUF_x
Input macro for Clock Network with
specific I/O standard
CLKBUF_LVDS/
LVPECL
LVDS or LVPECL input macro for Clock
Network
CLKINT
Internal clock interface
CLKBIBUF
Bidirectional
macro
with
input
dedicated to routed Clock Network
Y
PAD
CLKBUF
PAD
Y
CLKBUF_X
PADN
PADP
CLKBIBUF_LVPECL
Y
PADN
PADP
CLKBIBUF_LVDS
Y
AY
CLKINT
D
Y
E
PAD
CLKBIBUF
Table 3-7
I/O Standards within CLKBUF
Name
Description
CLKBUF_LVCMOS5
LVCMOS clock buffer with 5.0 V CMOS voltage level
CLKBUF_LVCMOS33
LVCMOS clock buffer with 3.3 V CMOS voltage level
CLKBUF_LVCMOS25
LVCMOS clock buffer with 2.5 V CMOS voltage level1
CLKBUF_LVCMOS18
LVCMOS clock buffer with 1.8 V CMOS voltage level
CLKBUF_LVCMOS15
LVCMOS clock buffer with 1.5 V CMOS voltage level
CLKBUF_LVCMOS12
LVCMOS clock buffer with 1.2 V CMOS voltage level
CLKBUF_PCI
PCI clock buffer
CLKBUF_PCIX
PCIX clock buffer
CLKBUF_GTL25
GTL clock buffer with 2.5 V CMOS voltage level1
CLKBUF_GTL33
GTL clock buffer with 3.3 V CMOS voltage level1
Notes:
1. Supported in only the IGLOOe and ProASIC3E devices
2. By default, the CLKBUF macro uses the 3.3 V LVTTL I/O technology.