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AR# 21764

Spartan-3/-3E - What is the definition of power-on?


In the Spartan-3 and the Spartan-3E FPGA DC and Switching Characteristics Data Sheets, the following note is included below the Quiescent Supply Current Characteristics table:

"The maximum numbers in this table indicate the minimum current each power rail requires in order for the FPGA to power-on successfully."

What is the definition of power-on in this context? Does it include the current needed for configuration?

The Spartan-3 Data Sheet is located at:


The Spartan-3E Data Sheet is located at:



In this context, power-on means that VCCINT, VCCAUX, and VCCO Bank 4 supplies reach their respective input threshold levels and the FPGA initializes successfully (INIT_B goes High). Once all three supplies are valid, the minimum current required to power-on the FPGA is equal to the worst-case quiescent current as specified in the Quiescent Supply Current Characteristics table.

Configuration is not included since configuration current always exceeds the quiescent current because the quiescent current specifications have no AC components as described in Note 1 below the Quiescent Supply Current Characteristics table.

Configuration current is not characterized; however, it depends on the configuration mode, rate, and data file that is loaded. The power supply should be designed based on the dynamic current consumption of the active design, which should easily account for the configuration current.

AR# 21764
Date 12/15/2012
Status Active
Type General Article