• State TI Thinks Resolved
  • Locked Locked
  • Replies 8 replies
  • Answers 1 answer
  • Subscribers 48 subscribers
  • Views 293 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BUF802: Clarification for Input clamping diode 100 mA current limit.

SuperGDx
Prodigy 30 points
Part Number: BUF802

We are using the BUF802 in CL mode like in the datasheet (March2022) fig. 9-6 +/-6V (50 Ohm), I would like to know how much power/voltage we can apply at the input to reach this 100 mA ? There is a resistor of 30 Ohm to limit the current in the path. For instance for a signal at 100 MHz, I estimate the limit at around +30 dBm (10.94V peak  or 7.7V RMS) Is it a correct estimate ?

  • 0
    TI__Genius 15661 points

    Hello SuperGDx,

    I can look into this information for you.

    Best,

    Alec

  • 0 in reply to Alec Saebeler
    TI__Genius 15661 points

    Hello SuperGDx,

    From my understanding of your questions, you are looking to determine what the maximum power/voltage you can apply at the inputs of the BUF802 would be?  is this correct?

    From the functional block diagram you can see the default input limits are set by the internal clamping diodes via CLH and CLL.  As you are not providing external diodes or an external signal to set CLH & CLL, this supply-referenced clamping limit is your default.

    Are you specifically asking how to push the device to its 100mA clamp limit on the input pin?  Or are you trying to check if your proposed signals will violate this input limit absolute maximum rating?

    Best,

    Alec

  • 0 in reply to Alec Saebeler
    Prodigy 30 points

    Hi Alec,

    Yes, what is the maximum input power to reach the limit of 100 mA for the circuit datasheet (March 2022) Fig 9-6  CL mode +/-6V 50 Ohm ?

    I am asking how to push the device to its 100mA clamp limit on the input pin.

    Thx for your support.

  • 0 in reply to SuperGDx
    TI__Genius 15661 points

    Hello SuperGDx,

    I am waiting to hear back from the team on the maximum input power.  I better understand now your intention to push the device to clamp at 100mA.

    Best,

    Alec

  • 0 in reply to Alec Saebeler
    Prodigy 30 points

    Hi Alec, Maybe I am the only one customer looking for this answer and I do not want to request too much effort from your team.

    I did some test myself with my EVB (Section "Standalone Configuration section ), slightly modified to bring it closer to "Composite configuration".

    My estimate was +30 dBm, I measured +32.9 dBm, +2.9 dBm more than predicted to pass 100 mA (RMS) into these diodes.

    You can also pass the message to your team, this BUF802 device perform very well.

    Best regards,

    SuperGDx 

  • 0 in reply to SuperGDx
    TI__Genius 15661 points

    Hello Super GDx,

    I am glad to hear you found results with your evaluation board.  Just to confirm, you tested the input structure and clamping of the BUF802 in BUF mode, without the precision amplifier?

    What input signal type and source instrument did you use?

    From the data you shared I have no objection; the BUF802 is performing as anticipated.

    Best,

    Alec

  • 0 in reply to Alec Saebeler
    Prodigy 30 points

    Hi Alec,

    See attached the image to answer to your questions. You can see highlighted in red the change done to the EVB circuit.

    You can also see the test equipment setup, signal 100MHz sinewave amplified, the filter makes the signal almost perfect attenuating harmonic presents.

    Best regards,

    SuperGDx

  • 0 in reply to SuperGDx
    TI__Genius 15661 points

    Hello SuperGDx,

    Thank you for your thorough response.

    Best,

    Alec