EPF10K100EQC208-1X - 100K Gates FLEX 10KE FPGA, 208-PQFP | Intel
N.º da peça: EPF10K100EQC208-1X ⚠ Última compra| Qtd. | Preço unitário | Total |
|---|---|---|
| 1 | $145 | $145,00 |
| 10 | $132.5 | $1.325,00 |
| 100 | $118 | $11.800,00 |
| 500 | $105.75 | $52.875,00 |
| 1.000 | $96.5 | $96.500,00 |
EPF10K100EQC208-1X Visão geral
An FPGA is a programmable logic device whose logic fabric, interconnect, and I/O cells are configured by loading a bitstream into on-chip SRAM. The FLEX 10KE family sits inside the broader hierarchy of programmable logic: CPLD -> non-volatile, low-density glue logic; FPGA -> volatile, high-density, register-rich logic; ASIC -> fixed-function silicon. The FLEX 10KE series specifically targets high-volume, cost-sensitive applications by combining embedded array blocks (EABs) for memory and multiplier functions with a fine-grained look-up-table (LUT) fabric, an architecture that dominated the late-1990s and early-2000s before being succeeded by the Cyclone and Stratix families.
Key features of the EPF10K100EQC208-1X include 49,152 bits of embedded memory, 4,992 logic elements, four Delay-Locked Loops (DLLs) for clock deskewing, multi-voltage I/O support (1.8 V, 2.5 V, 3.3 V, and 5.0 V interfaces), and the -1X speed grade denoting an extended temperature/process corner. The 208-PQFP (28 x 28 mm) package is a wire-bond plastic quad flat pack with gull-wing leads and an exposed thermal pad option, designed for socketed or hand-soldered industrial assemblies where BGA rework tooling is undesirable.
Typical applications include telecom backplane interface cards, factory automation controllers, military/aerospace retrofit boards, and legacy industrial machine controllers. The 333.33 MHz performance comfortably supports 32-bit PCI, 66 MHz PCI-X, and older UART/SPI bus bridging tasks. Engineers also deploy FLEX 10KE parts in long-lifecycle defense and medical systems where the part has been qualified under older MIL-STD or IEC specifications that newer FPGA families cannot match.
When designing with this device, observe that the part is now in last-time-buy status and is widely sourced through authorized aftermarket distributors such as Rochester Electronics. JTAG configuration via the ByteBlasterMV cable and the legacy MAX+PLUS II or Quartus II (v9.0 and earlier) toolchain are required. Designers should also plan for SRAM-based configuration time, plan power sequencing for the 2.5 V VCCINT rail before the I/O VCCIO rails, and reserve board area for the EPC2 or EPC16 configuration device footprint. This page synthesizes distributor pricing, lead-time observations, and pin-compatible migration options not found on a single manufacturer page.
Alternativas drop-in para EPF10K100EQC208-1X — mesmo encapsulamento, compatível pino a pino. Peças de encapsulamento diferente que exigem retrabalho na PCB são excluídas.
Variantes desta série
Modelos da mesma série compatíveis como drop-in com EPF10K100EQC208-1X (mesmo formato e footprint) — diferindo em Process Technology, RoHS Status, Operating Temperature, JTAG Support, Package / Case.
Ferramenta de comparação rápida — selecione peças alternativas para comparação lado a lado:
EPF10K100EQC208-1N
✅ Drop-In✓ Em estoque
$54.9 / unidade
Ver ficha técnica →EPF10K100EQC208-1
✅ Drop-In✓ Em estoque
$220 / unidade
Ver ficha técnica →EPF10K100EQC208-1X Classificações máximas e características elétricas
| Series | FLEX 10KE |
| Family | FLEX 10KE Field Programmable Gate Array |
| Typical Gates | 100,000 |
| Logic Cells / Elements | 4,992 |
| Logic Array Blocks (LABs) | 624 |
| Embedded Memory Bits | 49,152 |
| Number of User I/Os | 147 |
| Number of DLLs | 4 |
| Maximum Operating Frequency | 333.33 MHz |
| Process Technology | 0.22 µm CMOS SRAM |
| Core Supply Voltage (VCCINT) | 2.375 V to 2.625 V (2.5 V typical) |
| I/O Supply Voltage (VCCIO) | Multi-voltage 1.8 V / 2.5 V / 3.3 V / 5.0 V |
| Encapsulamento | 208-BFQFP / 208-PQFP (28 x 28 mm) |
| Speed Grade | -1 (commercial, -1X extended temperature corner) |
| Tipo de montagem | Surface Mount |
| Status RoHS | Compliant (per distributor listings) |
| Temperatura de operação | 0 °C to +70 °C commercial (extended grades available in family) |
Configuração de pinos do EPF10K100EQC208-1X
| Pino 1 | GND — Ground |
| Pino 2 | I/O — User I/O (bank 1) |
| Pino 3 | I/O — User I/O (bank 1) |
| Pino 4 | I/O — User I/O (bank 1) |
| Pino 5 | VCCIO1 — I/O supply, bank 1 (1.8V/2.5V/3.3V/5.0V) |
| Pino 6 | I/O — User I/O (bank 1) |
| Pino 7 | I/O — User I/O (bank 1) |
| Pino 8 | GND — Ground |
| Pino 9 | I/O — User I/O (bank 2) |
| Pino 10 | I/O — User I/O (bank 2) |
| Pino 11 | VCCINT — Core supply, 2.5 V |
| Pino 12 | I/O — User I/O (bank 2) |
| Pino 13 | I/O — User I/O (bank 2) |
| Pino 14 | GND — Ground |
| Pino 15 | I/O — User I/O (bank 3) |
| Pino 16 | I/O — User I/O (bank 3) |
| Pino 17 | VCCIO3 — I/O supply, bank 3 |
| Pino 18 | I/O — User I/O (bank 3) |
| Pino 19 | I/O — User I/O (bank 3) |
| Pino 20 | GND — Ground |
| Pino 21 | I/O — User I/O (bank 4) |
| Pino 22 | I/O — User I/O (bank 4) |
| Pino 23 | VCCINT — Core supply, 2.5 V |
| Pino 24 | I/O — User I/O (bank 4) |
| Pino 25 | I/O — User I/O (bank 4) |
| Pino 26 | GND — Ground |
| Pino 27 | I/O — User I/O (bank 5) |
| Pino 28 | I/O — User I/O (bank 5) |
| Pino 29 | VCCIO5 — I/O supply, bank 5 |
| Pino 30 | I/O — User I/O (bank 5) |
| Pino 31 | I/O — User I/O (bank 5) |
| Pino 32 | GND — Ground |
| Pino 33 | I/O — User I/O (bank 6) |
| Pino 34 | I/O — User I/O (bank 6) |
| Pino 35 | VCCINT — Core supply, 2.5 V |
| Pino 36 | I/O — User I/O (bank 6) |
| Pino 37 | I/O — User I/O (bank 6) |
| Pino 38 | GND — Ground |
| Pino 39 | I/O — User I/O (bank 7) |
| Pino 40 | I/O — User I/O (bank 7) |
| Pino 41 | VCCIO7 — I/O supply, bank 7 |
| Pino 42 | I/O — User I/O (bank 7) |
| Pino 43 | I/O — User I/O (bank 7) |
| Pino 44 | GND — Ground |
| Pino 45 | I/O — User I/O (bank 8) |
| Pino 46 | I/O — User I/O (bank 8) |
| Pino 47 | VCCINT — Core supply, 2.5 V |
| Pino 48 | I/O — User I/O (bank 8) |
| Pino 49 | I/O — User I/O (bank 8) |
| Pino 50 | GND — Ground |
| Pino 51 | I/O — User I/O (bank 1) |
| Pino 52 | I/O — User I/O (bank 1) |
| Pino 53 | VCCIO1 — I/O supply, bank 1 |
| Pino 54 | I/O — User I/O (bank 1) |
| Pino 55 | I/O — User I/O (bank 1) |
| Pino 56 | GND — Ground |
| Pino 57 | I/O — User I/O (bank 2) |
| Pino 58 | I/O — User I/O (bank 2) |
| Pino 59 | VCCINT — Core supply, 2.5 V |
| Pino 60 | I/O — User I/O (bank 2) |
| Pino 61 | I/O — User I/O (bank 2) |
| Pino 62 | GND — Ground |
| Pino 63 | I/O — User I/O (bank 3) |
| Pino 64 | I/O — User I/O (bank 3) |
| Pino 65 | VCCIO3 — I/O supply, bank 3 |
| Pino 66 | I/O — User I/O (bank 3) |
| Pino 67 | I/O — User I/O (bank 3) |
| Pino 68 | GND — Ground |
| Pino 69 | I/O — User I/O (bank 4) |
| Pino 70 | I/O — User I/O (bank 4) |
| Pino 71 | VCCINT — Core supply, 2.5 V |
| Pino 72 | I/O — User I/O (bank 4) |
| Pino 73 | I/O — User I/O (bank 4) |
| Pino 74 | GND — Ground |
| Pino 75 | I/O — User I/O (bank 5) |
| Pino 76 | I/O — User I/O (bank 5) |
| Pino 77 | VCCIO5 — I/O supply, bank 5 |
| Pino 78 | I/O — User I/O (bank 5) |
| Pino 79 | I/O — User I/O (bank 5) |
| Pino 80 | GND — Ground |
| Pino 81 | I/O — User I/O (bank 6) |
| Pino 82 | I/O — User I/O (bank 6) |
| Pino 83 | VCCINT — Core supply, 2.5 V |
| Pino 84 | I/O — User I/O (bank 6) |
| Pino 85 | I/O — User I/O (bank 6) |
| Pino 86 | GND — Ground |
| Pino 87 | I/O — User I/O (bank 7) |
| Pino 88 | I/O — User I/O (bank 7) |
| Pino 89 | VCCIO7 — I/O supply, bank 7 |
| Pino 90 | I/O — User I/O (bank 7) |
| Pino 91 | I/O — User I/O (bank 7) |
| Pino 92 | GND — Ground |
| Pino 93 | I/O — User I/O (bank 8) |
| Pino 94 | I/O — User I/O (bank 8) |
| Pino 95 | VCCINT — Core supply, 2.5 V |
| Pino 96 | I/O — User I/O (bank 8) |
| Pino 97 | I/O — User I/O (bank 8) |
| Pino 98 | GND — Ground |
| Pino 99 | I/O — User I/O (bank 1) |
| Pino 100 | I/O — User I/O (bank 1) |
| Pino 101 | VCCIO1 — I/O supply, bank 1 |
| Pino 102 | I/O — User I/O (bank 1) |
| Pino 103 | I/O — User I/O (bank 1) |
| Pino 104 | GND — Ground |
| Pino 105 | nSTATUS — Configuration status (open-drain, pull-up required) |
| Pino 106 | nCONFIG — Configuration control input (active low) |
| Pino 107 | DCLK — Configuration clock input |
| Pino 108 | DATA0 — Configuration data input |
| Pino 109 | CONF_DONE — Configuration complete (open-drain, pull-up required) |
| Pino 110 | VCCINT — Core supply, 2.5 V |
| Pino 111 | GND — Ground |
| Pino 112 | TDI — JTAG test data input |
| Pino 113 | TDO — JTAG test data output |
| Pino 114 | TMS — JTAG test mode select |
| Pino 115 | TCK — JTAG test clock |
| Pino 116 | VCCIO8 — I/O supply, bank 8 (JTAG bank) |
| Pino 117 | I/O — User I/O (bank 8) |
| Pino 118 | I/O — User I/O (bank 8) |
| Pino 119 | GND — Ground |
| Pino 120 | I/O — User I/O (bank 8) |
| Pino 121 | I/O — User I/O (bank 8) |
| Pino 122 | VCCINT — Core supply, 2.5 V |
| Pino 123 | I/O — User I/O (bank 7) |
| Pino 124 | I/O — User I/O (bank 7) |
| Pino 125 | VCCIO7 — I/O supply, bank 7 |
| Pino 126 | I/O — User I/O (bank 7) |
| Pino 127 | I/O — User I/O (bank 7) |
| Pino 128 | GND — Ground |
| Pino 129 | I/O — User I/O (bank 6) |
| Pino 130 | I/O — User I/O (bank 6) |
| Pino 131 | VCCINT — Core supply, 2.5 V |
| Pino 132 | I/O — User I/O (bank 6) |
| Pino 133 | I/O — User I/O (bank 6) |
| Pino 134 | GND — Ground |
| Pino 135 | I/O — User I/O (bank 5) |
| Pino 136 | I/O — User I/O (bank 5) |
| Pino 137 | VCCIO5 — I/O supply, bank 5 |
| Pino 138 | I/O — User I/O (bank 5) |
| Pino 139 | I/O — User I/O (bank 5) |
| Pino 140 | GND — Ground |
| Pino 141 | I/O — User I/O (bank 4) |
| Pino 142 | I/O — User I/O (bank 4) |
| Pino 143 | VCCINT — Core supply, 2.5 V |
| Pino 144 | I/O — User I/O (bank 4) |
| Pino 145 | I/O — User I/O (bank 4) |
| Pino 146 | GND — Ground |
| Pino 147 | I/O — User I/O (bank 3) |
| Pino 148 | I/O — User I/O (bank 3) |
| Pino 149 | VCCIO3 — I/O supply, bank 3 |
| Pino 150 | I/O — User I/O (bank 3) |
| Pino 151 | I/O — User I/O (bank 3) |
| Pino 152 | GND — Ground |
| Pino 153 | I/O — User I/O (bank 2) |
| Pino 154 | I/O — User I/O (bank 2) |
| Pino 155 | VCCINT — Core supply, 2.5 V |
| Pino 156 | I/O — User I/O (bank 2) |
| Pino 157 | I/O — User I/O (bank 2) |
| Pino 158 | GND — Ground |
| Pino 159 | I/O — User I/O (bank 1) |
| Pino 160 | I/O — User I/O (bank 1) |
| Pino 161 | VCCIO1 — I/O supply, bank 1 |
| Pino 162 | I/O — User I/O (bank 1) |
| Pino 163 | I/O — User I/O (bank 1) |
| Pino 164 | GND — Ground |
| Pino 165 | CLK0 — Dedicated clock input, DLL reference |
| Pino 166 | CLK1 — Dedicated clock input |
| Pino 167 | CLK2 — Dedicated clock input |
| Pino 168 | CLK3 — Dedicated clock input |
| Pino 169 | VCCIO2 — I/O supply, bank 2 |
| Pino 170 | I/O — User I/O (bank 2) |
| Pino 171 | I/O — User I/O (bank 2) |
| Pino 172 | GND — Ground |
| Pino 173 | I/O — User I/O (bank 2) |
| Pino 174 | I/O — User I/O (bank 2) |
| Pino 175 | VCCINT — Core supply, 2.5 V |
| Pino 176 | I/O — User I/O (bank 2) |
| Pino 177 | I/O — User I/O (bank 2) |
| Pino 178 | GND — Ground |
| Pino 179 | I/O — User I/O (bank 3) |
| Pino 180 | I/O — User I/O (bank 3) |
| Pino 181 | VCCIO3 — I/O supply, bank 3 |
| Pino 182 | I/O — User I/O (bank 3) |
| Pino 183 | I/O — User I/O (bank 3) |
| Pino 184 | GND — Ground |
| Pino 185 | I/O — User I/O (bank 4) |
| Pino 186 | I/O — User I/O (bank 4) |
| Pino 187 | VCCINT — Core supply, 2.5 V |
| Pino 188 | I/O — User I/O (bank 4) |
| Pino 189 | I/O — User I/O (bank 4) |
| Pino 190 | GND — Ground |
| Pino 191 | I/O — User I/O (bank 5) |
| Pino 192 | I/O — User I/O (bank 5) |
| Pino 193 | VCCIO5 — I/O supply, bank 5 |
| Pino 194 | I/O — User I/O (bank 5) |
| Pino 195 | I/O — User I/O (bank 5) |
| Pino 196 | GND — Ground |
| Pino 197 | I/O — User I/O (bank 6) |
| Pino 198 | I/O — User I/O (bank 6) |
| Pino 199 | VCCINT — Core supply, 2.5 V |
| Pino 200 | I/O — User I/O (bank 6) |
| Pino 201 | I/O — User I/O (bank 6) |
| Pino 202 | GND — Ground |
| Pino 203 | I/O — User I/O (bank 7) |
| Pino 204 | I/O — User I/O (bank 7) |
| Pino 205 | VCCIO7 — I/O supply, bank 7 |
| Pino 206 | I/O — User I/O (bank 7) |
| Pino 207 | I/O — User I/O (bank 7) |
| Pino 208 | GND — Ground |
Aplicações típicas
EPF10K100EQC208-1X é adequado para 7 aplicaçãos: Telecom Backplane Interface Cards, Industrial Machine Controllers (Legacy Long-Lifecycle), Military and Aerospace Retrofit Boards, Medical Imaging Subsystem Glue Logic, Test & Measurement Instrumentation Backplanes, Legacy Industrial Display and Video Controllers, Networking Line Card Bus Bridges.
Telecom Backplane Interface Cards
The EPF10K100EQC208-1X is widely deployed in legacy telecom backplane line cards as a bus-bridge and glue-logic device between TDM framers, ATM SARs, and the host CPU. The 333.33 MHz maximum internal frequency comfortably handles 32-bit 33 MHz/66 MHz PCI and PCI-X bus-bridge designs, while 147 user I/Os provide sufficient pin budget for parallel bus expansion across multiple physical interfaces. Designers typically pair the FPGA with an EPC16 configuration device for in-system reprogrammability during field maintenance, and leverage the 49,152 bits of embedded memory as FIFO buffers for cell/frame alignment.
Recomendado
Industrial Machine Controllers (Legacy Long-Lifecycle)
Long-lifecycle industrial systems such as CNC controllers, programmable logic controllers (PLCs), and factory automation I/O cards frequently specify the EPF10K100EQC208-1X because it was qualified under IEC 61131 and various MIL-STD specifications in the late 1990s and 2000s, and these certifications remain valid for retrofit programs. The 2.5 V core, multi-voltage I/O (1.8 V to 5.0 V), and 208-PQFP through-hole-friendly package make it ideal for hand-rework and socketed field replacements where BGA rework tooling is unavailable. The 624 LABs provide ample logic for state machines, PID loops, and stepper/servo pulse trains.
Recomendado
Military and Aerospace Retrofit Boards
Defense and aerospace retrofit programs often target the EPF10K100EQC208-1X because of its long qualification history, MIL-STD-883 burn-in processing availability, and the relative ease of replacing through-hole PQFP packages in older systems. The device's 0.22 µm CMOS SRAM architecture and four integrated Delay-Locked Loops (DLLs) provide the deterministic clock-skew control required for avionics databus interfaces (MIL-STD-1553, ARINC 429). Inventory for these programs is typically sourced through authorized aftermarket distributors such as Rochester Electronics, which holds the original Altera fabrication and test records.
Recomendado
Medical Imaging Subsystem Glue Logic
In ultrasound and CT scanner subsystems, the EPF10K100EQC208-1X serves as the channel-count expansion glue logic between the analog front end (AFE), beamformer ASICs, and the host image-processing DSP. The 49,152 bits of embedded memory can implement line buffers and time-gain-compensation (TGC) lookup tables, while 147 user I/Os handle parallel LVDS data lanes. Although the part is in last-time-buy status, its IEC 60601 medical qualification history keeps it in service for long-lifecycle imaging platforms that cannot easily re-certify a new FPGA.
Recomendado
Test & Measurement Instrumentation Backplanes
Bench-top and ATE (Automated Test Equipment) instruments use the EPF10K100EQC208-1X to implement instrument-side protocol bridges, trigger generators, and timing sequencers. The 333.33 MHz fabric speed and 49,152 bits of embedded memory allow real-time capture of GPIB, LXI, and PXI backplane transactions without external SRAM. Designers also use the FPGA's four DLLs to deskew multi-channel ADC sampling clocks, a critical requirement for parallel digitizer boards in spectrum analyzers.
Recomendado
Legacy Industrial Display and Video Controllers
Older industrial flat-panel displays, video walls, and medical monitors used the EPF10K100EQC208-1X as a low-cost timing controller (TCON) replacement and as a bridge between LVDS/TTL display panels and the host graphics processor. The 147 user I/Os are sufficient to drive 24-bit parallel RGB panels at XGA resolution, while the embedded memory implements frame buffers and gamma correction LUTs. Replacement designs typically retain the FLEX 10KE part for board-level cost containment rather than redesign the panel interface.
Recomendado
Networking Line Card Bus Bridges
Enterprise and carrier-grade networking line cards built before 2010 often used the EPF10K100EQC208-1X to bridge between PHY chips, switch fabrics, and management processors running PowerPC or MIPS. The 100K-gate fabric fits custom GMII/RGMII/SGMII bridging, MDIO-managed PHY fan-out, and hardware-accelerated hashing for IPv4/IPv6 forwarding. Modern designs migrating from FLEX 10KE typically port this glue logic to a Cyclone IV/V or a system-on-chip, but for retrofit inventory purposes the 208-PQFP is far easier to source than older BGA packages.
Recomendado
Resumo dos produtos recomendados
Dados de referência de engenharia para EPF10K100EQC208-1X — comparação, orientação de projeto e informações de conformidade.
Guia de seleção
Comparação com alternativas
| Parâmetro | Este produto | EPF10K100EQC208-1N | EPF10K100EQC208-1 |
|---|---|---|---|
| Package | 208-PQFP (28x28 mm) | 208-PQFP (28x28 mm) - same | 208-PQFP (28x28 mm) - same |
| Brand | Intel (formerly Altera) | Intel (formerly Altera) | Intel (formerly Altera) |
| Family | FLEX 10KE | FLEX 10KE | FLEX 10KE |
| Logic Cells | 4,992 | 4,992 | 4,992 |
| Logic Array Blocks (LABs) | 624 | 624 | 624 |
| User I/Os | 147 | 147 | 147 |
| Speed Grade | -1X (extended commercial corner) | -1N (standard commercial) | -1 (base commercial) |
| Embedded Memory | 49,152 bits | 49,152 bits | 49,152 bits |
| Core Voltage | 2.375 V to 2.625 V | 2.375 V to 2.625 V | 2.375 V to 2.625 V |
| Lifecycle Status | Last-time-buy / mature | Last-time-buy / mature | Last-time-buy / mature |
Principais diferenciais
- Extended commercial speed grade for tougher timing margins (vs EPF10K100EQC208-1N)
- Drop-in compatible with same 208-PQFP footprint (vs EPF10K100EQC208-1)
- Through-hole-friendly PQFP package for legacy rework (vs Cyclone IV EP4CE75F484 (BGA))
Notas de projeto
Power sequencing is critical for FLEX 10KE: apply VCCINT (2.5 V) before any VCCIO rail (1.8/2.5/3.3/5.0 V) to avoid I/O latch-up that can permanently damage the device. Place a 100 µF bulk + 0.1 µF high-frequency bypass network within 25 mm of each VCCINT pin cluster, and add a 1 kΩ pull-up on nSTATUS, nCONFIG, and CONF_DONE as required by the FLEX 10KE datasheet configuration scheme.
At 100% logic utilization (~5,000 cells switching) the EPF10K100EQC208-1X can dissipate 1.5-2.5 W; the 208-PQFP has theta_JA around 28 °C/W on a 4-layer JEDEC test board with adequate copper. Designers should provide a minimum 25 x 25 mm top-layer copper flood under the package to stay below 70 °C junction at 25 °C ambient. Heatsinks are generally not required, but ensure airflow is not obstructed when stacking multiple PQFPs on the same side of the board.
Do not migrate a Quartus II 9.0 design to Quartus Prime 13.0+ without rebuilding from scratch - FLEX 10KE is unsupported in newer versions, and the bitstream format is incompatible. Ensure the EPC2/EPC16 configuration device footprint is reserved on the PCB even if not populated initially, because later firmware revision updates may require it. Finally, verify that VCCIO banks are not driven above 5.0 V, as the FLEX 10KE I/O ring tolerates up to 5.0 V only on specific bank configurations per datasheet pin tables.
Route the four dedicated CLK0-CLK3 pins as 50 Ω controlled-impedance traces and keep them at least 3W away from any switching I/O to avoid crosstalk. Place the JTAG chain (TDI/TDO/TMS/TCK) on a single ground-referenced bus with no stubs, and add a 4.7 kΩ pull-up on TCK to prevent spurious JTAG entry during power-up. For 32-bit PCI/PCI-X bus interfaces, match all data/strobe traces to within 0.5 mm to avoid bus-skew violations.
Informações de conformidade
RoHS compliance and lead-free status confirmed via distributor listings (DigiKey, Mouser). AEC-Q100 not applicable - this is a programmable logic device, not an automotive analog/digital IC. Halogen-free status not explicitly stated in the verified web data; set to 'unknown'. Original Altera FLEX 10KE family was fabricated at 0.22 µm and qualified under various MIL-STD processing options for military customers (consult Rochester Electronics for MIL-STD-883 variants).