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Altera_Forum's avatar
Altera_Forum
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15 years ago

Ripple for input power supply

What is the minimum input voltage Ripple required for the cyclone II FPGA voltage of 1.2V and 3.3V. The spec is not given in the datasheet.

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    Do you mean the maximum allowed ripple of the supply voltage of the FPGA?

    Do you refer to the ripple visible on the output pin of the FPGA?

    Can you explain better?
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    --- Quote Start ---

    The spec is not given in the datasheet.

    --- Quote End ---

    I think it's well defined. Simply assume, that the instantaneous voltage has to keep the specified operation conditions, about +/- 4% for VCCINT. In addition, for devices without voltage regulator for analog PLL supply, a lower high frequency ripple may be required for stable PLL operation. This applies e.g. for Cyclone II VCCA. Pay attention to the VCCA bypass and filter recommendations.