Some Cypress Flash devices provide the Vio option besides the Vcc core voltage. What if Vcc and Vio are coming from different supplies? - KBA203733

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Question:

Some Cypress Flash devices provide the Vio option besides the Vcc core voltage. What if Vcc and Vio are coming from different supplies? 

 

Answer:

With this scenario, VCC (3.3V) was coming up before VIO (2.5V) with a time lag of up to 50ms. The concern was related to the Flash power-up initialization. This scenario, however, should be okay. Ensure that VIO is not higher than Vcc during power up. Lagging should not be an issue. RESET# must remain low until after VIO eventually comes up to desired level.