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BUF22821 - STATINx, STATOUTx

Kawai
Guru 19775 points
Other Parts Discussed in Thread: BUF22821

Hi Team,

I have some questions about Gamma Buffer, BUF22821, from our customer in design.
Could you pelase tell me about the followings ?

1) What is "STATIC GAMMA CHANNEL" and how can you use STATINx / STATOUTx ?

2) If you do not use this function should you just tie STATINx pins to GND ?
     Please let me know if you need an to pull down by resistor.

Best Regards,
Kawai

  • 0
    TI__Expert 6930 points

    Hi Takushi-san,

    Thank you for the questions.  Please see my reply next to your question.

    1) What is "STATIC GAMMA CHANNEL" and how can you use STATINx / STATOUTx ?

    Answer:

    2) If you do not use this function should you just tie STATINx pins to GND ?
         Please let me know if you need an to pull down by resistor.

    Answer: If you do not plan to use the STATx buffers then please configure the STATINH pin to pin 12 (VS) and the STATINL pin to ground (pins 28 and 11).  You do not need a resistor, the connection may be direct.   Please leave the STATOUTx pins unconnected (floating).

  • 0 in reply to Edward Mullins
    Guru 19775 points

    Hi Ed-san,

    Thank you for your reply.
    Please let me confirm about your answer.

    For Qeustion 1, I am understanding that these pins will be used when the monitor does not use the Dynamic Gamma Control, only using static gamma curve. Am I correct ?

    This is from my curiosity but why do you need to connect the STATINH to VS ?
    It seems that there is only a buffer inside STATINH pin.
    Would there be a problem if you connect STATINH pin to GND ?

    Thanks and Best Regards,
    Kawai

  • 0 in reply to Kawai
    TI__Expert 6930 points

    Hi Kawai-san,

    Your understanding is basically correct, please keep in mind that the two static gamma channels are additional gamma channels that are not programmable.  They were a special request by a customer at the time of development and were added to meet their request.  It is likely that you may not need to use them.

    I suggest to connect the STATINH pin to Vs as that is the way the device is tested in production as noted in the condition of Vin = 18V (same as Vs when tested).  I also noted from Figure 4 in the data sheet that the output of the STATOUTH buffer seems limited to 1V minimum.  I do not know if this is a limitation imposed by the input to the buffer or the output of the buffer, but connecting the STATINH input to ground will be outside the typical operating range for that buffer and while it is probably OK to do so, I do not have any data to support this configuration.