Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs

ID 814346
Date 11/27/2024
Public
Document Table of Contents

5.8.9.1. Guidelines for External SDA and SCL Signals via HPS I/O in the Board Design

I3C bus operates in both open-drain and push-pull modes. Pull-ups are required during open-drain mode to make sure that the bus is pulled high when no device on the bus is pulling it low. The following figures show the pull-up resistors on the I3C bus.

Figure 207. I3C Controller and Device(s) with Pull-Up Resistor on I3C Bus (ES Device)
Figure 208. I3C Controller and Device(s) with Pull-Up Resistor on I3C Bus (Production Device)

The I3C controller can support up to 8 slave devices, but the actual number depends on factors like trace length, capacitive load per device, and the device types (I2C versus I3C), as these impact clock frequency requirements. For bus load capacitance up to 50 pF, Altera recommends using a 1kΩ pull-up resistor.

Altera recommends that you use the IBIS model to verify the electrical performance of your design. Refer to the Agilex™ 5 Device HPS and SDM I/O IBIS Models.

For more information, refer to the Pin Connection Guidelines: Agilex™ 5 FPGAs and SoCs for the respective functional pins.