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Altera_Forum's avatar
Altera_Forum
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13 years ago

Clock Voltage on Max7000

Hi there!

I'm doing a PCB design which includes a microcontroller and a MAX7000 CPLD. As the controller's IOs work on 3.3V we decided to run the MAX7000's IOs also on 3.3V. The core is using 5V

In the MAX7000 datasheet I couldn't find any information about the clock voltage. Can i use a 5V oscillator, even if the IO voltage is on 3.3V?

Thanks for your support

Simon

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    13 years ago

    If you read the MAX7000 data sheet thoroughly, you'll notice:

    - Input buffers are supplied from VCCINT and thus independent of VCCIO.

    - MAX7000 inputs have a TTL level specification, minimal high level is 2.0 V. 3.3V CMOS and 5V CMOS/TTL levels are fine to drive the inputs, including clock.
  • Altera_Forum's avatar
    Altera_Forum
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    13 years ago

    Thank you for your advice. In a few days i'll see if it was correct...:)