AR# 5770

描述

How much current can the I/O sink or source?

解决方案

This information is in the device data sheet, under "DC Characteristic - Over Recommended Operating Conditions." Check for the VOH and VOL rows, then find the Test Conditions column. This will show what the maximum guaranteed sink/source currents are for VOL and VOH (respectively).

The devices are capable of delivering/sinking more current; however, at values beyond those stated in the data sheet, the voltage and output timing delays can no longer be guaranteed.

IV curves can be found for the:

CoolRunner XPLA3 family in the device data sheets:

http://www.xilinx.com/xlnx/xweb/xil_publications_index.jsp

CoolRunner-II family in the device data sheets:

http://www.xilinx.com/xlnx/xweb/xil_publications_index.jsp

XC9500/XL family in (Xilinx XAPP150): "IV Curves for Various Device Families."

Note that the IV curves will not directly match up with the limits given in the data sheets. This is because the IV curves are for a typical device under typical operating conditions. The limits given in the data sheets are guaranteed for worst-case operating conditions and all process variations.

For other common CPLD questions, please see the CPLD FAQ: (Xilinx Answer 24167)