XC7K355T FPGA: Resources, FFG901 Pinout and Link Planning

February 21, 2026 · Published by WWDParts

XC7K355T is a Kintex-7 FPGA with a resource mix that emphasizes DSP, memory and serial connectivity. It is not simply a smaller version of every higher-numbered Kintex-7 device. Package availability, ordinary I/O and serial-lane count can move in different directions across the family. Start with those constraints before comparing utilization percentages or choosing a migration target.

Verified XC7K355T resource baseline

Logic cells	356,160
CLB slices / 6-input LUTs	55,650 / 222,600
Flip-flops	445,200
DSP48E1 slices	1,440
Block RAM	715 blocks of 36 Kb; 25,740 Kb total
GTX / maximum user I/O	24 / 300
Package in DS180	FFG901; 31 × 31 mm, 1.0 mm ball pitch

References: AMD 7 Series Overview, DS180 v2.6.1, AMD CLB Resources, UG474 v1.9 and AMD Memory Resources, UG473 v1.14. Logic cells and LUTs are different metrics; use the physical resource categories in the implementation report for design budgeting.

Use the correct package and bank map

The DS180 device/package table lists FFG901 for XC7K355T, with 300 HR I/O and no HP I/O. FBG484, FFG676 and FFG900 should not be presented as its package options. Download the matching file from AMD Kintex-7 package and pinout files and match it to the ordered part before creating or approving the schematic symbol.

The 901-ball package includes dedicated power, configuration and transceiver connections. Do not translate that ball count into general-purpose signals. Make a bank allocation sheet listing each interface, voltage, clock and reserved signal. Run the tool pin checks before routing the PCB; finding an incompatible bank assignment at that stage is much less disruptive than after layout.

Use the actual package drawing and assembly information for the footprint and thermal design. A generic exposed-pad or die-attach-paddle description is not a specification for this BGA. Confirm the mechanical arrangement, board stack-up and intended cooling solution instead of adding a central solder pad from an unrelated package pattern.

Serial lanes need a complete throughput budget

Consider an illustrative design receiving 16 lanes at 6.25 Gb/s each, with an assumed 8b/10b-encoded protocol. The serial total is 100 Gb/s. Removing only that encoding overhead leaves 80 Gb/s, or 10 GB/s, before packet headers, gaps and other overhead. This example is not a supported-protocol or sustained-throughput claim.

A downstream 256-bit interface clocked at an assumed 250 MHz has a raw capacity of 64 Gb/s, or 8 GB/s. It cannot carry that example payload continuously even before stalls. A 512-bit interface at the same assumed frequency has a raw capacity of 128 Gb/s; it offers arithmetic headroom, but still needs routing, timing and flow-control validation. A finite FIFO cannot solve a permanent average-rate mismatch.

Map the physical lanes and their reference clocks together. AMD GTX Reference Clocks and PLLs, XAPP1249 v1.3 describes four channels per quad and the shared QPLL versus channel PLLs. Record which links share clock resources, which reset together and how one failed link affects the remaining channels. Leave enough observability to count errors on each lane during bring-up.

For electrical limits, use AMD Kintex-7 Electrical Characteristics, DS182 v2.19 Table 56. Its 12.5 Gb/s maximum is conditional on the applicable -3 FF case and supply requirements; it is not the rate of every XC7K355T order code. The table also excludes line rates between 8.0 and 9.8 Gb/s. Confirm that the desired protocol rate, PLL settings and exact grade form a supported combination.

A larger part number is not a universal upgrade

XC7K410T offers more logic and DSP resources, but DS180 lists 16 GTX transceivers for it versus 24 for XC7K355T. Its 1,540 DSP slices are 100 above 1,440: an increase of about 6.94%, not 25%. User-I/O maxima also differ: 500 for 410T versus 300 for 355T. See AMD 7 Series Overview, DS180 v2.6.1. These are selection dimensions, not an automatic upgrade path.

A project that needs twenty serial channels cannot approve a move to a device with sixteen just because the LUT count is higher. Conversely, a design dominated by parallel I/O can have a different preference. Compare a requirement vector: used LUTs, registers, DSPs, memory-block shapes, serial channels, bank voltages, clocks and package pins. Run the same implementation and interface review for every candidate.

Changing FPGA vendors adds toolchain, IP, timing-constraint and board-design work. Similar density does not establish equivalent pinout, configuration behavior or protocol implementation. Treat those parts as candidates for a redesign study, not drop-in replacements.

Release checks for a multi-link board

Implement a minimal lane test before adding the full DSP path. Keep a record of the actual part, reference clocks, transceiver settings and board revision.
Test sustained traffic and deliberate backpressure. Compare sent and received sequence numbers to distinguish lost data from a link that merely remains locked.
Exercise lane reset and clock loss independently. Verify whether shared clock resources cause expected or unexpected effects on other links.
Budget power for the intended active-lane and logic workload, then validate temperatures on the assembled board. A family-level efficiency statement cannot substitute for that test.

Ordering and manufacturer references

Send the full XC7K355T ordering code, quantity, required delivery date and any packaging or documentation requirements through the WWDParts RFQ list. Price, availability and delivery terms are confirmed in the written quotation.

Technical content reviewed October 13, 2026. The budgets and validation steps here are engineering examples, not measured performance, qualification results or replacement approvals. Use the applicable manufacturer document revision and exact order code for design release.