EP1S80B956C7N Altera, EP1S80B956C7N Datasheet - Page 327

• Manufacturer Part Number: EP1S80B956C7N
• Description: IC STRATIX FPGA 80K LE 956-BGA
• Manufacturer: Altera
• Series: Stratix®r

Specifications of EP1S80B956C7N

• Number Of Logic Elements/cells: 79040
• Number Of Labs/clbs: 7904
• Total Ram Bits: 7427520
• Number Of I /o: 683
• Voltage - Supply: 1.425 V ~ 1.575 V
• Mounting Type: Surface Mount
• Operating Temperature: 0°C ~ 85°C
• Package / Case: 956-BGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Number Of Gates: -

Altera Corporation
July 2005
frequency, then the output frequency starts at a higher value than desired
as the PLL locks. If the system cannot tolerate this, the clkena signal can
disable the output clocks until the PLL locks.
The pfdena signals control the phase frequency detector (PFD) output
with a programmable gate. If you disable the PFD, the VCO operates at
its last set value of control voltage and frequency with some long-term
drift to a lower frequency. The system continues running when the PLL
goes out of lock or the input clock is disabled. By maintaining the last
locked frequency, the system has time to store its current settings before
shutting down. You can either use your own control signal or a clkloss
status signal to trigger pdfena.
The clkena signals control the enhanced PLL regional and global
outputs. Each regional and global output port has its own clkena signal.
The clkena signals synchronously disable or enable the clock at the PLL
output port by gating the outputs of the g and l counters. The clkena
signals are registered on the falling edge of the counter output clock to
enable or disable the clock without glitches.
Figure 1–7
PLL can remain locked independent of the clkena signals since the loop-
related counters are not affected. This feature is useful for applications
that require a low power or sleep mode. Upon re-enabling, the PLL does
not need a resynchronization or relock period. The clkena signal can
also disable clock outputs if the system is not tolerant to frequency
overshoot during resynchronization.
The extclkena signals work in the same way as the clkena signals, but
they control the external clock output counters (e0, e1, e2, and e3). Upon
re-enabling, the PLL does not need a resynchronization or relock period
unless the PLL is using external feedback mode. In order to lock in
external feedback mode, the external output must drive the board trace
back to the FBIN pin.
shows the waveform example for a PLL clock port enable. The
General-Purpose PLLs in Stratix & Stratix GX Devices
Stratix Device Handbook, Volume 2
1–17