Common FPGA I/O Interface Standards
FPGAs (Field-Programmable Gate Arrays) support various I/O interface standards for communication with external devices. These standards define voltage levels, signaling methods, and protocols. Below are the most commonly used ones:
📌 1. Single-Ended Standards
(One signal line per data bit, referenced to ground.)
| Standard | Voltage | Speed | Use Case |
|---|---|---|---|
| LVCMOS (Low-Voltage CMOS) | 1.2V, 1.8V, 2.5V, 3.3V | < 500 Mbps | GPIO, slow peripherals |
| LVTTL (Low-Voltage TTL) | 3.3V | < 100 Mbps | Legacy systems, microcontrollers |
| HSTL (High-Speed Transceiver Logic) | 1.5V | ~ 200 Mbps | Memory interfaces (QDR, DDR) |
| SSTL (Stub-Series Terminated Logic) | 1.8V, 2.5V | ~ 400 Mbps | DDR SDRAM interfaces |
📌 2. Differential Standards
(Uses two complementary signals for noise immunity & high speed.)
| Standard | Voltage | Speed | Use Case |
|---|---|---|---|
| LVDS (Low-Voltage Differential Signaling) | 350 mV (differential) | 1+ Gbps | High-speed serial links (cameras, displays) |
| RSDS (Reduced Swing Differential Signaling) | 200-400 mV | ~ 500 Mbps | LCD displays |
| TMDS (Transition-Minimized Differential Signaling) | 500 mV | 3.4+ Gbps | HDMI, DVI video |
| MIPI D-PHY (Mobile Industry Processor Interface) | 200 mV | 1.5+ Gbps | Cameras, displays (CSI-2, DSI) |
| PCIe (Peripheral Component Interconnect Express) | 800 mV | 2.5-32 GT/s | High-speed data transfer |
📌 3. Memory Interface Standards
| Standard | Type | Speed | Use Case |
|---|---|---|---|
| DDRx (Double Data Rate) | SSTL/HSTL | 800 Mbps - 3.2 Gbps | DDR3/4/5 SDRAM |
| LPDDR (Low-Power DDR) | SSTL | ~ 4.2 Gbps | Mobile devices |
| QDR (Quad Data Rate) | HSTL | ~ 500 Mbps | High-bandwidth SRAM |
📌 4. High-Speed Serial Standards
| Standard | Protocol | Speed | Use Case |
|---|---|---|---|
| USB (Universal Serial Bus) | USB 2.0/3.0 | 480 Mbps - 10 Gbps | Peripherals, data transfer |
| SATA (Serial ATA) | 8b/10b encoding | 1.5 - 6 Gbps | Storage devices |
| Ethernet (1G/10G/25G) | IEEE 802.3 | 1 - 100 Gbps | Networking |
| JESD204B/C (Serial Data Converter Interface) | 8b/10b | 12.5 Gbps | ADCs/DACs (RF applications) |
📌 5. Legacy & Industrial Standards
| Standard | Voltage | Speed | Use Case |
|---|---|---|---|
| RS-232 | ±3V to ±15V | < 1 Mbps | Serial communication (UART) |
| RS-485 | ±1.5V to ±6V | 10 Mbps | Industrial multi-drop buses |
| CAN (Controller Area Network) | 2V (differential) | 1 Mbps | Automotive, industrial control |
📌 6. FPGA-Specific I/O Standards
| Standard | FPGAs Supporting It | Use Case |
|---|---|---|
| SelectIO™ (Xilinx) | Xilinx FPGAs | Configurable I/O banks |
| LVDS, LVCMOS (Intel/Altera) | Intel FPGAs | General-purpose I/O |
| BLVDS (Bus LVDS) | Xilinx, Intel | Backplane communication |
🔹 Choosing the Right Standard
For low-speed control: LVCMOS, LVTTL
For high-speed data: LVDS, PCIe, MIPI
For memory interfaces: SSTL, HSTL (DDR)
For industrial use: RS-485, CAN
评论
发表评论