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SN74LVCH322244A: Look for 32bit buffer and single-ended 16bit ADC

Lin Hsian
Expert 1580 points

Part Number: SN74LVCH322244A

Hi,

This project application in optical fingerprint sensing solution.

And need AFE(Analog front end) input impedance higher than 50Mega ohm, so select buffer as well.

We need multi channel in buffer and select SN74LVCH322244A which is 32-BIT BUFFER/DRIVER,WITH 3-STATE OUTPUTS.

It's suitable for us, isn't ?

And the other question is what's ADC parts can match SN74LVCH322244A?

Regards,

Lin

  • 0
    TI__Guru* 96591 points
    Hi Lin,
    I would recommend talking with our ADC experts -- they might be able to help you out. I think that you are looking for something very different from a standard logic buffer with bus hold (which is what part you have selected). The I/O impedance on that device is at least one order of magnitude less than 50 Mohm.

    I will notify the appropriate team to look into this thread.
  • 0 in reply to Emrys Maier
    Expert 1580 points
    Hi,
    Could you please give me a update, thanks.
    I would like to search ADC parts which can match SN74LVCH322244A or 32-BIT BUFFER/DRIVER compatible with 32bits ADC.

    Warm Regards,
    Lin
  • 0 in reply to Lin Hsian
    Expert 1580 points
    Hi,
    let me summarize the questions:
    1. TI 128 channel ADC： DDC1128 is current-input. Our sensor is the voltage output. Thus, is it possible to find the 128-channel voltage-input ADC ?
    2. If the above solution is fail. Could you please provide 32 or 16 in/out buffers and correspondent 16-channel 16-bit ADC ? I believe can find this combination. For example, we have found a 32 in/out buffer: (SN74LVCH322244A, 32-BIT BUFFER/DRIVER,WITH 3-STATE OUTPUTS) Is it suitable ? What is the corresponding 16-channel 16-bit ADC ?

    Warm Regards,
    Lin
  • 0 in reply to Lin Hsian
    TI__Guru* 96591 points
    Hi Lin,
    I have notified the appropriate team. I understand that they are currently travelling, so their response may be delayed.
  • 0 in reply to Lin Hsian
    TI__Guru**** 168605 points
    Hi Lin,

    We do not have a voltage input ADC with 128 channels. The DDC1128 was meant to be used with photo-diodes. I suspect you are thinking about using the SN74LVCH322244A as the input stage to the DDC1128 and that won't work - you cannot drive the DDC from a digital buffer. What is the nature of your sensor?
  • 0 in reply to Tom Hendrick
    Expert 1580 points
    Hi Tom,
    The sensor is photo-diode on the glass (panel) for fingerprint application, but sends out the voltage signal (0 ~ 5V) to ADC.
    Since TI has no voltage input ADC with 128 channels. Could you please suggest the adequate combination of AFE (buffer and ADC). Maybe 4 pcs or 8 pcs of 32 or 16 in/out buffers, and 16 or 32 channel ADC ?

    Warm Regards,
    Lin