3.1. Guideline: VREF Sources and VREF Pins
3.2. Guideline: Observe Device Absolute Maximum Rating for 3.0 V Interfacing
3.3. Guideline: Voltage-Referenced and Non-Voltage Referenced I/O Standards
3.4. Guideline: Do Not Drive I/O Pins During Power Sequencing
3.5. Guideline: Stratix® 10 I/O Buffer During Power Up, Configuration, and Power Down
3.6. Guideline: Maximum DC Current Restrictions
3.7. Guideline: Use Only One Voltage for All 3 V I/O Banks
3.8. Guideline: I/O Standards Limitation for Stratix® 10 TX 400
3.9. Guideline: I/O Standards Limitation for Stratix® 10 GX 400 and SX 400
4.1.2.2. Output and Output Enable Paths
The output delay element sends data to the pad through the output buffer.
Each LVDS I/O output path contains two stages of DDIOs, which are half-rate and full-rate.
The 3 V I/Os do not support DDIOs.
Figure 28. Simplified View of Single-Ended GPIO Output Path
Figure 29. Output Path Waveform in DDIO Mode with Half-Rate Conversion
Figure 30. Simplified View of Output Enable Path
The difference between the output path and output enable (OE) path is that the OE path does not contain full-rate DDIO. To support packed-register implementations in the OE path, a simple register operates as full-rate DDIO. For the same reason, only one half-rate DDIO is present.
The OE path operates in the following three fundamental modes:
- Bypass—the core sends data directly to the delay element, bypassing all DDIOs.
- Packed Register—bypasses half-rate DDIO.
- SDR output at half-rate—half-rate DDIOs convert data from full-rate to half-rate.
In Stratix® 10 devices, each 3 V I/O bank supports only two output enables (OE) for its eight single-ended I/Os.
Note: The GPIO Intel® FPGA IP and OCT Intel® FPGA IP support OCT during power up and user mode on single-directional input or output pins. The GPIO IP does not support dynamic OCT of bidirectional pins. For applications that require dynamic OCT control for bidirectional pins, refer to the related information.