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PGA870: 16bit alternative

lina lin wei
Prodigy 30 points
Part Number: PGA870
Other Parts Discussed in Thread: LMH6517, PGA281

Hi,

I am current designing a data acquisition board for my research. I am planning on using the ADC AD7381 . However, I was having a hard time finding an appropriate PGA to go with it. The PGA870 looked promising but it's for 14bit adc, and I was wondering if you had a 16bit equivalent to it.

Thank you

  • 0
    TI__Genius 15555 points

    Hello Lina,

    Unfortunately there are no differential PGA alternatives, however you may want to look into the LMH6517 for a VGA option.

    Best,

    Hasan Babiker

  • 0 in reply to Hasan Babiker31
    Prodigy 30 points

    Hi Hasan,

    Thanks a lot. Are there any single ended PGA alternatives? I was just worried that the VGA would affect the performance of the ADC.

    A bit of context about my project: We are currently collecting data from LEDs(750nm and 850nm wavelength) of varying light intensity with photodiodes. The LEDs have varying light intensities depending on their distance to the different photodiodes. We don't want to saturate the photodiodes. My goal right is increase acquisition rate by using PGA's with the ADC instead of varying the light intensity of the LEDs. The current controller that we are using has a slow ramp rate of 15mA/msec. This becomes quite substantial as we have a lot of the LEDs and photodiodes on our design.

    Best regards,

    Lina

  • 0 in reply to lina lin wei
    TI__Genius 15555 points

    Hello Lina,

    Another alternative would be the PGA281, Is there a reason why a VGA would cause issues with your ADC?

    Best,

    Hasan Babiker

  • 0 in reply to Hasan Babiker31
    Prodigy 30 points

    Hi Hasan,

    Thanks a lot! I was just worried that the VGA would introduce unwanted noise into the analog signal, and I heard that PGA's are more suited for High-Precision measurements. Correct me, if I'm wrong tho. I'm still new in this domain.

    Best regards,

    Lina

  • 0 in reply to lina lin wei
    TI__Genius 15555 points

    Hey Lina,

    Sorry about the confusion, but PGAs and VGAs are essentially the same type of part with a different naming convention. You may be thinking of VCAs where gain is controlled by different voltage levels.

    Best,

    Hasan Babiker