Power Management User Guide: Agilex™ 5 FPGAs and SoCs

ID 813161
Date 7/08/2024
Public
Document Table of Contents

4.3.2. Guidelines: Connecting External Reference to the Agilex™ 5 Voltage Reference Pins

The Agilex™ 5 voltage sensor has two dedicated voltage reference pins, VREFP_ADC and VREFN_ADC. Follow these guidelines when you connect an external voltage reference to the VREFP_ADC and VREFN_ADC pins.
  • To minimize noise coupling to the power rail, Altera recommends that you keep the external VREF source as close as possible to the VREFP_ADC and VREFN_ADC pins.
  • Route the reference traces as a tightly-coupled differential pair to the package ball with ground shielding.
  • You must place a 10 µF and a 1 µF board capacitors to decouple the VREFP_ADC and VREFN_ADC pins.
  • Place the 1 µF board capacitor as close as possible to the package balls.
Figure 10. Board Capacitors to Decouple VREFP_ADC and VREFN_ADC Pins