EP1S20F484C6N Altera, EP1S20F484C6N Datasheet - Page 337

• Manufacturer Part Number: EP1S20F484C6N
• Description: IC STRATIX FPGA 20K LE 484-FBGA
• Manufacturer: Altera
• Series: Stratix®r

Specifications of EP1S20F484C6N

• Number Of Logic Elements/cells: 18460
• Number Of Labs/clbs: 1846
• Total Ram Bits: 1669248
• Number Of I /o: 361
• Voltage - Supply: 1.425 V ~ 1.575 V
• Mounting Type: Surface Mount
• Operating Temperature: 0°C ~ 85°C
• Package / Case: 484-FBGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Number Of Gates: -

Altera Corporation
July 2005
because of the low-voltage swing. The differential LVDS signal also
allows for EMI rejection within the signal. Therefore, this situation may
not require spread-spectrum technology.
Description
Stratix and Stratix GX device enhanced PLLs feature spread-spectrum
technology to reduce the EMI emitted from the device. The enhanced PLL
provides up to a 0.5% down spread (–0.5%) using a triangular, also
known as linear, modulation profile. The modulation frequency is
programmable and ranges from approximately 30 to 150 kHz. The spread
percentage is based on the clock input to the PLL and the m and n settings.
Spread-spectrum technology reduces the peak energy by 2 to 5 dB at the
target frequency. However, this number is dependent on bandwidth and
the m and n counter values and can vary from design to design.
Spread percentage, also known as modulation width, is defined as the
percentage that the design modulates the target frequency. A negative
(–) percentage indicates a down spread, a positive (+) percentage
indicates an up spread, and a ( ) indicates a center spread. Modulation
frequency is the frequency of the spreading signal or how fast the signal
sweeps from the minimum to the maximum frequency. Down-spread
modulation shifts the target frequency down by half the spread
percentage, centering the modulated waveforms on a new target
frequency.
The m and n counter values are toggled at the same time between two
fixed values. The loop filter then slowly changes the VCO frequency to
provide the spreading effect, which results in a triangular modulation.
An additional spread-spectrum counter (shown in
modulation frequency.
technology is implemented in the Stratix device enhanced PLL.
General-Purpose PLLs in Stratix & Stratix GX Devices
Figure 1–15
shows how spread-spectrum
Stratix Device Handbook, Volume 2
Figure
1–15) sets the
1–27