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AR# 18457

CPLD CoolRunner-II - What is the effect of power sequencing?


What is the recommended power sequence for powering CoolRunner-II CPLDs?


Power (Vccint, Vccio, Vccaux) can be applied in any order without causing damage to the device.

In the following, Vccio refers to both Vccio as well as Vccaux. Vccio and Vccaux can be powered in any order with respect to each other.

It is recommended that Vccint be powered before Vccio, but this is not required. Doing so will allow the device to be configured and ready to function the instant Vccio is applied. This might result in additional current being drawn while Vccio ramps up. The amount of extra current is not determined, as it is entirely dependant on the loading of the I/Os on the board.

Applying Vccio before Vccint might result in less power while Vccint is powering up. However, the I/Os might glitch Low when Vccint comes up. This will not damage the device.

AR# 18457
Date 12/15/2012
Status Active
Type General Article