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Altera_Forum
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14 years ago

JTAG power consumption

I am using a MAXII EPM240T100I5N device and I want to determine what the power consumption of the device is when it is running in JTAG (boundary-scan) mode when the device is running without any configuration on it. I have checked the device resources thoroughly and there is no indication as to how I would find this out. Does anyone have any ideas where I can find this information?

8 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    MAX II is a SRAM based device, power consumption is mainly caused by switching actions. I think, without JTAG activity, you can expect the standby supply current specified in the datasheet.

  • Altera_Forum's avatar
    Altera_Forum
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    Assuming that in the worst case, all the boundary-scan capable pins were active and driving the output, what kind of power would that draw?

  • Altera_Forum's avatar
    Altera_Forum
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    I understand that it will depend on what load is attached to each pin, but I am trying to establish the worst-case current sourcing to use as a benchmark. In other words, what is the maximum current that each JTAG output can supply assuming a 3.3V output? Is there anywhere that such information is available?

  • Altera_Forum's avatar
    Altera_Forum
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    --- Quote Start ---

    the maximum current that each JTAG output can supply

    --- Quote End ---

    I presume, you mean IO pins configured as output.

    IO pins have no current limiting function and you shouldn't short or overload them without risking to damage the chip. A maximum current of 25 mA has to be kept according to the datasheet. When shorted, a pin can sink or source up to 60 mA, which isn't permitted as continuous current.
  • Altera_Forum's avatar
    Altera_Forum
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    Yes FvM, that is what I meant. I did not phrase it technically correctly. The information regarding the maximum allowed output current and the shorting is useful and is what I was looking for. Where can I obtain a reference containing such information?

  • Altera_Forum's avatar
    Altera_Forum
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    Just look at the MAX II datasheet, Chapter 5. DC & Switching Characteristic.