【应用手册】Cyclone III Configuration Interface Guidelines with EPCS Devices This application note describes the methods to interface a Cyclone III® device to a serial configuration device (EPCS) using Cyclone III I/O voltages of 3.0 V and 2.5 V, in addition to the standard 3.3 V. This application note discusses the electrical specifications, timing requirements, signal integrity analysis, and board physical design guidelines for the supported active serial (AS) configuration schemes. On Cyclone III devices, bank 1 is used for AS configuration signals and for user I/Os. The I/O voltage for Cyclone III AS configuration signals must be compatible with the operating voltage of Altera EPCS devices and must not conflict with the intended I/O voltages for other bank 1 signals. The Altera EPCS devices support supply voltage from 2.7 V to 3.6 V, which enables it to be operated at 3.3 V or 3.0 V. This application note shows the methods to use the Cyclone III bank 1 I/O voltages of 3.0 V and 2.5 V with the EPCS device. Additionally, at any of the Cyclone III I/O voltages of 3.3/3.0/2.5 V, this application note shows how to create a robust electrical and physical board design to interface with an EPCS device using single and multidevice AS configuration. You can create your design based on the signal integrity analysis and physical design constraints in this application note to achieve a successful AS configuration. Cyclone III Configuration Interface Guidelines with EPCS Devices June 2008, version 1.0 Application Note 523 Introduction This application note describes the methods to interface a Cyclone III device to a serial configuration device (EPCS) using Cyclone III I/O voltages of 3.0 V and 2.5 V, in addition to the standard 3.3 V. This application note discusses the electrical specifications, timing requirements, signal integrity analysis, and board physical desi……