EP1S25F672C7 Altera, EP1S25F672C7 Datasheet - Page 103

• Manufacturer Part Number: EP1S25F672C7
• Description: IC STRATIX FPGA 25K LE 672-FBGA
• Manufacturer: Altera
• Series: Stratix®r

Specifications of EP1S25F672C7

• Number Of Logic Elements/cells: 25660
• Number Of Labs/clbs: 2566
• Total Ram Bits: 1944576
• Number Of I /o: 473
• Voltage - Supply: 1.425 V ~ 1.575 V
• Mounting Type: Surface Mount
• Operating Temperature: 0°C ~ 85°C
• Package / Case: 672-FBGA
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Number Of Gates: -
• Other names: 544-1118

Figure 2–53. Clock Switchover Circuitry
Altera Corporation
July 2005
INCLK0
INCLK1
There are two possible ways to use the clock switchover feature.
■
■
SMCLKSW
Use automatic switchover circuitry for switching between inputs of
the same frequency. For example, in applications that require a
redundant clock with the same frequency as the primary clock, the
switchover state machine generates a signal that controls the
multiplexer select input on the bottom of
secondary clock becomes the reference clock for the PLL.
Use the clkswitch input for user- or system-controlled switch
conditions. This is possible for same-frequency switchover or to
switch between inputs of different frequencies. For example, if
inclk0 is 66 MHz and inclk1 is 100 MHz, you must control the
switchover because the automatic clock-sense circuitry cannot
monitor primary and secondary clock frequencies with a frequency
difference of more than ±20%. This feature is useful when clock
sources can originate from multiple cards on the backplane,
requiring a system-controlled switchover between frequencies of
operation. You can use clkswitch together with the lock signal to
trigger the switch from a clock that is running but becomes unstable
and cannot be locked onto.
MUXOUT
Sense
Enhanced PLL
Clock
n Counter
State Machine
Switch-Over
Δt
Stratix Device Handbook, Volume 1
Figure
PFD
2–53. In this case, the
Stratix Architecture
CLK0_BAD
CLK1_BAD
Active Clock
CLKLOSS
CLKSWITCH
FBCLK
2–89