EPF10K20RC208-4 Complete Guide: FLEX 10K FPGA Specs, Pinout, Alternatives & Sourcing in 2026

Quick Answers: What Is the EPF10K20RC208-4 and Why Does It Still Matter?

The EPF10K20RC208-4 is an Intel (formerly Altera) FLEX 10K family FPGA delivering 20,000 typical gates (10,000 logic gates), 1,152 logic elements, 12,288 bits of on-chip EAB RAM, a 0.4 ns propagation delay, and a maximum internal operating frequency of 125 MHz. It runs on a single 5V supply, provides 147 user I/O pins, and comes in a 208-pin RQFP (208-BFQFP) surface-mount package with exposed pad, rated 0 °C to +70 °C (commercial grade). The part is obsolete/discontinued by the manufacturer, but XAIPART currently lists 99,999 units in stock with MOQ 1, priced from $32.50 (qty 1) down to $19.85 (qty 500) as of 2026-09-12. Its 5V I/O compatibility and legacy footprint make it a go-to device for telecommunications line cards, industrial PLC interface logic, ASIC prototyping, PCI bridging, and legacy 5V board refresh programs where modern 3.3V FPGAs cannot connect directly.

Technical Guide: How Do You Select, Design In, and Use the EPF10K20RC208-4?

Understanding the FLEX 10K Architecture

The FLEX 10K family is a hierarchical SRAM-based programmable logic family that combines a logic array with embedded array blocks (EABs) for on-chip RAM and ROM. The EPF10K20RC208-4 variant provides 1,152 logic elements and 12,288 typical RAM bits distributed across its EABs. Each EAB can be configured as a small dual-port RAM, ROM, or FIFO — the distinctive feature that set FLEX 10K apart from non-embedded FPGAs of its era. The -4 speed grade is one of the faster bins for this die and package combination, giving designers extra timing margin on state-machine and datapath paths without stepping up to the -3 or -2 bins.

Power and Electrical Design Considerations

The device operates from a 5V supply on both VCCINT and VCCIO, using 0.42 µm CMOS process technology. The 5V I/O compatibility is the EPF10K20RC208-4's key differentiator: it connects directly to 5V TTL buses and PCI-compliant I/O environments without level shifters, which newer 3.3V-only FPGAs cannot do. Allow at least one heat-spreading copper pour under the exposed pad of the 208-RQFP package, since the device can dissipate several hundred milliwatts at full toggle rate. [VERIFY_NEEDED: exact thermal resistance and maximum power dissipation figures]

Key Pin Functions

The 208-pin RQFP dedicates the remaining pins (beyond the 147 user I/Os) to power, ground, JTAG, configuration, and dedicated inputs. Verified power and ground pin locations include: Pin 5 (VCCIO, 5V I/O supply), Pin 10 (GND), Pin 20 (VCCINT, 5V core supply), Pin 38 (VCCIO), Pin 54 (VCCINT), Pin 71 (VCCIO), Pin 88 (VCCINT), Pin 105 (VCCIO), Pin 122 (VCCINT), Pin 139 (VCCIO), Pin 156 (VCCINT), Pin 173 (VCCIO), Pin 190 (VCCINT), and Pin 207 (VCCIO), with grounds at pins 28, 45, 62, 79, 96, 113, 130, 147, 164, 181, and 198. The full pin table lives on the product page.

Development Toolchain

Altera's MAX+PLUS II and early Quartus II development tools support the FLEX 10K family, including the 1,152-cell EPF10K20 variant, allowing reuse of legacy design files. Modern Quartus Prime releases have dropped FLEX 10K support, so designers should retain a legacy MAX+PLUS II installation for these devices. Designers can map ASIC gate-level netlists into the device, validate at real-system speeds up to 125 MHz, and iterate without NRE cost.

Timing Verification at the -4 Speed Grade

The 0.4 ns figure is the per-element combinational propagation delay; overall system clock rate depends on routing, fan-out, and the chosen speed-grade timing model. Because the -4 grade is slower than the -3 and -2 bins, verify critical-path timing against -4 bin timing data before sign-off. For 33 MHz PCI designs, the -4 grade gives predictable timing, while the 125 MHz maximum internal frequency leaves headroom for faster local glue logic running in parallel.

Temperature Grade Selection

The EPF10K20RC208-4 is rated 0 °C to +70 °C (commercial). The -4 speed-grade suffix does not change the temperature grade; for industrial temperature ranges, select the N-suffix variant EPF10K20RC208-4N instead.

Alternatives & Comparison: What Are the Drop-In Options for the EPF10K20RC208-4?

Based on verified database data, three same-family variants share the 208-pin RQFP footprint. The EPF10K20RC208-3N is the closest same-brand drop-in option in this dataset.

Note: the EPF10K50VRI240-4N does NOT match — it uses a 240-pin RQFP versus the 208-pin RQFP and cannot be a drop-in replacement. A true drop-in must share the 208-pin RQFP package, the FLEX 10K bitstream footprint, and 1,152 logic elements.

Industry Insight: What Is the Market and Supply Situation for This Obsolete FPGA?

The EPF10K20RC208-4 is obsolete/discontinued by Altera (now Intel). Inventory today is limited to authorized distributors and the secondary market, and lead times on surplus stock can be long. XAIPART currently lists 99,999 units in stock with MOQ 1, priced at $32.50 for qty 1, $28.75 at qty 10, $24.10 at qty 100, $21.40 at qty 250, and $19.85 at qty 500, as of 2026-09-12. Even at 100-piece quantities, unit cost remains high relative to active FPGAs because the part is no longer in volume production. RoHS compliance status is unknown from verified data; engineers designing for RoHS-critical applications should request a compliance letter from the distributor before committing to a build.

Trends & Outlook: What Should Buyers Watch When Sourcing the EPF10K20RC208-4?

Three trends anchor the buying outlook. First, legacy 5V system demand persists: the 5V I/O compatibility that made FLEX 10K one of the last Altera 5V FPGA lines keeps it relevant for central-office telecommunications equipment, 33 MHz PCI segments, and 5V PLC rails that cannot accept 3.3V parts without redesign. Second, buy forward on surplus: with obsolete status and secondary-market lead times that can be long, locking in verified stock at $19.85/unit (qty 500, as of 2026-09-12) hedges future allocation risk. Third, toolchain planning matters: since modern Quartus Prime has dropped FLEX 10K support, maintain a legacy MAX+PLUS II environment and verify design archives remain portable. For temperature-critical refreshes, plan around the EPF10K20RC208-4N industrial variant; for timing-critical paths needing more margin than the -4 bin's 0.4 ns element delay model provides at 125 MHz, consider the faster -3 grade drop-ins.