XA6SLX25T-2CSG324Q

XA Spartan-6 Automotive FPGA Family Overview
DS170 (v1.3) December 13, 2012 www.xilinx.com
Product Specification 4
SLICEL
One quarter (25%) of the XA Spartan-6 FPGA slices are SLICELs, which contain all the features of the SLICEM except the
memory/shift register function.
SLICEX
One half (50%) of the XA Spartan-6 FPGA slices are SLICEXs. The SLICEXs have the same structure as SLICELs except
the arithmetic carry option and the wide multiplexers.
Clock Management
Each XA Spartan-6 FPGA has up to six CMTs, each consisting of two DCMs and one PLL, which can be used individually
or cascaded.
DCM
The DCM provides four phases of the input frequency (CLKIN): shifted 0°, 90°, 180°, and 270° (CLK0, CLK90, CLK180, and
CLK270). It also provides a doubled frequency CLK2X and its complement CLK2X180. The CLKDV output provides a
fractional clock frequency that can be phase-aligned to CLK0. The fraction is programmable as every integer from 2 to 16,
as well as 1.5, 2.5, 3.5 . . . 7.5. CLKIN can optionally be divided by 2. The DCM can be a zero-delay clock buffer when a clock
signal drives CLKIN, while the CLK0 output is fed back to the CLKFB input.
Frequency Synthesis
Independent of the basic DCM functionality, the frequency synthesis outputs CLKFX and CLKFX180 can be programmed to
generate any output frequency that is the DCM input frequency (F
IN
) multiplied by M and simultaneously divided by D, where
M can be any integer from 2 to 32 and D can be any integer from 1 to 32.
Phase Shifting
With CLK0 connected to CLKFB, all nine CLK outputs (CLK0, CLK90, CLK180, CLK270, CLK2X, CLK2X180, CLKDV,
CLKFX, and CLKFX180) can be shifted by a common amount, defined as any integer multiple of a fixed delay. A fixed DCM
delay value (fraction of the input period) can be established by configuration and can also be incremented or decremented
dynamically.
Spread-Spectrum Clocking
The DCM can accept and track typical spread-spectrum clock inputs, provided they abide by the input clock specifications
listed in the Spartan-6 FPGA Data Sheet: DC and Switching Characteristics. XA Spartan-6 FPGAs can generate a spread-
spectrum clock source from a standard fixed-frequency oscillator.
PLL
The PLL can serve as a frequency synthesizer for a wider range of frequencies and as a jitter filter for incoming clocks in
conjunction with the DCMs. The heart of the PLL is a voltage-controlled oscillator (VCO) with a frequency range of
400 MHz to 1,080 MHz, thus spanning more than one octave. Three sets of programmable frequency dividers (D, M, and O)
adapt the VCO to the required application.
The pre-divider D (programmable by configuration) reduces the input frequency and feeds one input of the traditional PLL
phase comparator. The feedback divider (programmable by configuration) acts as a multiplier because it divides the VCO
output frequency before feeding the other input of the phase comparator. D and M must be chosen appropriately to keep the
VCO within its controllable frequency range.
The VCO has eight equally spaced outputs (0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°). Each can be selected to drive
one of the six output dividers, O0 to O5 (each programmable by configuration to divide by any integer from 1 to 128).
XA Spartan-6 Automotive FPGA Family Overview
DS170 (v1.3) December 13, 2012 www.xilinx.com
Product Specification 5
Clock Distribution
Each XA Spartan-6 FPGA provides abundant clock lines to address the different clocking requirements of high fanout, short
propagation delay, and extremely low skew.
Global Clock Lines
In each XA Spartan-6 FPGA, 16 global-clock lines have the highest fanout and can reach every flip-flop clock. Global clock
lines must be driven by global clock buffers, which can also perform glitchless clock multiplexing and the clock enable
function. Global clocks are often driven from the CMTs, which can completely eliminate the basic clock distribution delay.
I/O Clocks
I/O clocks are especially fast and serve only the localized input and output delay circuits and the I/O serializer/deserializer
(SERDES) circuits, as described in the I/O Logic section.
Block RAM
Every XA Spartan-6 FPGA has between 12 and 268 dual-port block RAMs, each storing 18 Kb. Each block RAM has two
completely independent ports that share only the stored data.
Synchronous Operation
Each memory access, whether read or write, is controlled by the clock. All inputs, data, address, clock enables, and write
enables are registered. The data output is always latched, retaining data until the next operation. An optional output data
pipeline register allows higher clock rates at the cost of an extra cycle of latency.
During a write operation in dual-port mode, the data output can reflect either the previously stored data, the newly written
data, or remain unchanged.
Programmable Data Width
Each port can be configured as 16K × 1, 8K × 2, 4K × 4, 2K × 9 (or 8), 1K × 18 (or 16), or 512 x 36 (or 32).
The x9, x18, and x36 configurations include parity bits. The two ports can have different aspect ratios.
Each block RAM can be divided into two completely independent 9 Kb block RAMs that can each be configured to any
aspect ratio from 8K x 1 to 512 x 18, with 256 x 36 supported in simple dual-port mode.
Memory Controller Block
Most XA Spartan-6 devices include dedicated memory controller blocks (MCBs), each targeting a single-chip DRAM (either
DDR, DDR2, DDR3, or LPDDR), and supporting access rates of up to 800 Mb/s.
The MCB has dedicated routing to predefined FPGA I/Os. If the MCB is not used, these I/Os are available as general
purpose FPGA I/Os. The memory controller offers a complete multi-port arbitrated interface to the logic inside the XA
Spartan-6 FPGA. Commands can be pushed, and data can be pushed to and pulled from independent built-in FIFOs, using
conventional FIFO control signals. The multi-port memory controller can be configured in many ways. An internal 32-, 64-,
or 128-bit data interface provides a simple and reliable interface to the MCB.
The MCB can be connected to 4-, 8-, or 16-bit external DRAM. The MCB, in many applications, provides a faster DRAM
interface compared to traditional internal data buses, which are wider and are clocked at a lower frequency. The FPGA logic
interface can be flexibly configured irrespective of the physical memory device.
Digital Signal Processing—DSP48A1 Slice
DSP applications use many binary multipliers and accumulators, best implemented in dedicated DSP slices. All XA
Spartan-6 FPGAs have many dedicated, full-custom, low-power DSP slices, combining high speed with small size, while
retaining system design flexibility.
Each DSP48A1 slice consists of a dedicated 18 × 18 bit two’s complement multiplier and a 48-bit accumulator, both capable
of operating at up to 390 MHz. The DSP48A1 slice provides extensive pipelining and extension capabilities that enhance
XA Spartan-6 Automotive FPGA Family Overview
DS170 (v1.3) December 13, 2012 www.xilinx.com
Product Specification 6
speed and efficiency of many applications, even beyond digital signal processing, such as wide dynamic bus shifters,
memory address generators, wide bus multiplexers, and memory-mapped I/O register files. The accumulator can also be
used as a synchronous up/down counter. The multiplier can perform barrel shifting.
Input/Output
The number of I/O pins varies from 132 to 328, depending on device and package size. Each I/O pin is configurable and can
comply with a large number of standards, using up to 3.3V. The Spartan-6 FPGA SelectIO Resources User Guide describes
the I/O compatibilities of the various I/O options. With the exception of supply pins and a few dedicated configuration pins,
all other package pins have the same I/O capabilities, constrained only by certain banking rules. All user I/O is bidirectional;
there are no input-only pins.
All I/O pins are organized in four banks. Each bank has several common V
CCO
output supply-voltage pins, which also
powers certain input buffers. Some single-ended input buffers require an externally applied reference voltage (V
REF
). There
are several dual-purpose V
REF
-I/O pins in each bank. In a given bank, when I/O standard calls for a V
REF
voltage, each V
REF
pin in that bank must be connected to the same voltage rail and can not be used as an I/O pin.
I/O Electrical Characteristics
Single-ended outputs use a conventional CMOS push/pull output structure, driving High towards V
CCO
or Low towards
ground, and can be put into high-Z state. Many I/O features are available to the system designer to optionally invoke in each
I/O in their design, such as weak internal pull-up and pull-down resistors, strong internal split-termination input resistors,
adjustable output drive-strengths and slew-rates, and differential termination resistors. See the Spartan-6 FPGA SelectIO
Resources User Guide for more details on available options for each I/O standard.
I/O Logic
Input and Output Delay
This section describes the available logic resources connected to the I/O interfaces. All inputs and outputs can be configured
as either combinatorial or registered. Double data rate (DDR) is supported by all inputs and outputs. Any input or output can
be individually delayed by up to 256 increments. This is implemented as IODELAY2. The identical delay value is available
either for data input or output. For a bidirectional data line, the transfer from input to output delay is automatic. The number
of delay steps can be set by configuration and can also be incremented or decremented while in use.
Because these tap delays vary with supply voltage, process, and temperature, an optional calibration mechanism is built into
each IODELAY2:
For source synchronous designs where more accuracy is required, the calibration mechanism can (optionally)
determine dynamically how many taps are needed to delay data by one full I/O clock cycle, and then programs the
IODELAY2 with 50% of that value, thus centering the I/O clock in the middle of the data eye.
A special mode is available only for differential inputs, which uses a phase-detector mechanism to determine whether
the incoming data signal is being accurately sampled in the middle of the eye. The results from the phase-detector logic
can be used to either increment or decrement the input delay, one tap at a time, to ensure error-free operation at very
high bit rates.
ISERDES and OSERDES
Many applications combine high-speed bit-serial I/O with slower parallel operation inside the device. This requires a
serializer and deserializer (SerDes) inside the I/O structure. Each input has access to its own deserializer (serial-to-parallel
converter) with programmable parallel width of 2, 3, or 4 bits. Where differential inputs are used, the two serializers can be
cascaded to provide parallel widths of 5, 6, 7, or 8 bits. Each output has access to its own serializer (parallel-to-serial
converter) with programmable parallel width of 2, 3, or 4 bits. Two serializers can be cascaded when a differential driver is
used to give access to bus widths of 5, 6, 7, or 8 bits.
When distributing a double data rate clock, all SerDes data is actually clocked in/out at single data rate to eliminate the
possibility of bit errors due to duty cycle distortion. This faster single data rate clock is either derived via frequency
multiplication in a PLL, or doubled locally in each IOB by differentiating both clock edges when the incoming clock uses
double data rate.

XA6SLX25T-2CSG324Q

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Manufacturer:
Xilinx
Description:
FPGA - Field Programmable Gate Array
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