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Altera_Forum
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14 years ago

Cyclone III 3.3 volt tolerant?

I am using an Altera Cyclone III development board.

Into pin J4 which is suppose to be 2.5 volts - is it 3.3volt tolerant?

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    I can only guess, which board and pin J4 you mean. Altera Cyclone III 3C120 Development Board? Signal HSMA_TX_D_P11 connected to FPGA pin J4?

    All I/O pins are 3.3V tolerant, you should however keep the tolerated overshoot range for safe Cyclone III operation.
  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    Yes, you can use 3.0V for security consideration instead of 3.3v, it may damage the cyc3.

  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    You can have damaging overshoots at 3.0V too, it's better to ensure that the cyc3 pins are well protected against overshoots (clamping diodes, and/or a buffer close to FPGA as an example) rather than just reduce the I/O voltage by 0.3V.