Differential HSTL Class I Termination - Differential HSTL Class I Termination - UG861

Spartan UltraScale+ FPGAs SelectIO Resources User Guide (UG861)

Document ID
UG861
Release Date
2026-04-28
Revision
1.1 English

The following figure shows a sample circuit illustrating a termination technique for differential HSTL class-I (1.2V, 1.5V, or 1.8V) with unidirectional termination. In a specific circuit, all drivers and receivers must be at the same voltage level (1.2V, 1.5V, or 1.8V). They are not interchangeable (that is, HDIFF_HSTL_I_18 should only interface with HSTL_I_18).

Figure 1. Differential HSTL Class I (1.2V, 1.5V, or 1.8V) Unidirectional Termination

The following figure shows a sample circuit illustrating a termination technique for differential HSTL class-I (1.2V, 1.5V, or 1.8V) with bidirectional termination. In a specific circuit, all drivers and receivers must be at the same voltage level (1.2V, 1.5V, or 1.8V). They are not interchangeable (that is, DIFF_HSTL_I_18 should only interface with DIFF_HSTL_I_18).

Figure 2. Differential HSTL Class I (1.2V, 1.5V, or 1.8V) Bidirectional Termination

The following figure shows a sample circuit illustrating a termination technique for differential HSTL class-I (1.2V, 1.5V, or 1.8V) with unidirectional DCI termination. In a specific circuit, all drivers and receivers must be at the same voltage level (1.2V, 1.5V, or 1.8V). They are not interchangeable (that is, DIFF_HSTL_I_DCI should only interface with DIFF_HSTL_I_DCI). Only HP I/O banks support these DCI standards.

Figure 3. Differential HSTL Class I (1.2V, 1.5V, or 1.8V) DCI Unidirectional Termination

The following figure shows a sample circuit illustrating a termination technique for differential HSTL class-I (1.2V, 1.5V, or 1.8V) with bidirectional DCI termination. In a specific circuit, all drivers and receivers must be at the same voltage level (1.2V, 1.5V, or 1.8V). They are not interchangeable (that is, DIFF_HSTL_I_DCI should only interface with DIFF_HSTL_I_DCI). Only HP I/O banks support these DCI standards.

Figure 4. Differential HSTL Class I (1.2V, 1.5V, or 1.8V) DCI Bidirectional Termination