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Altera_Forum's avatar
Altera_Forum
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17 years ago

ByteBlaster 2 current consumption

Hi,

I am using ByteBlaster 2 to burn my MAX2 device. My whole circuit current consumption is approx. 100mA. When I connect the ByteBlaster 2, the current consumption goes to approx. 250mA. After the burning is done, the current consumption becomes extremely high, more then 1A, until I disconnect the ByteBlaster 2. Is it tupposed to be that way? Why does it need such a big current?

Thanks

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    17 years ago

    From the ByteBlaster II datasheet the operating current is 50mA max.

    It looks like you might have some contention. Is your design driving any of the JTAG pins used for configuration?

    Maybe when your device is configured your FPGA is using the TDI (Or other) pin as an output and driving back against the Byte Blaster .

    I would check the pin out of your device and see if you are reusing the config pins as outputs.

    Also check what the state of unused pins is set to.

    Good luck
  • Altera_Forum's avatar
    Altera_Forum
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    17 years ago

    My device isn't using any of the JTAG pins for anything but JTAG. As I understand it, these pins are dedicated for JTAG functionality and can't be used for anything else. Am I supposed to set them in a special way?

    I use the "Unused pins" option to put all the unused pins in tri-state.

    Note that the very high power consumption happens after the burning is finished, as if something shortens after burning.
  • Altera_Forum's avatar
    Altera_Forum
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    17 years ago

    OK. I am not totally sure about whether you can reuse JTAG pins on MAX2 devices. I'd need to look it up!

    You should still probably check that all your output pins are not connected to other outputs or power rails external to the PLD.

    Obviously after programming the device it enters operating mode i.e. it will start driving any outputs so that could explain why you see the higher current after config. I am not sure why disconnecting the ByteBlaster reduces the current. It still suggests to me that something is driving against a ByteBlaster output.