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LM49120 dynamic range

Paul Ternes
Prodigy 90 points
Other Parts Discussed in Thread: LM49120

Hi

 

What is the dynamic range for the LM49120?  Specifically, how close to the rails can the input, output and internal signal chain get?

 

Thanks 

Paul

  • 0
    TI__Guru**** 189399 points

    Hi, Paul,

    You can calculate the voltage swing based on the plots in the data sheet under different conditions.

    Usually in audio circuits, we do not worry about rail-to-rail inputs, so figure the inputs should be kept at  leave 0.5V away from the rails as a good rule of thumb.

    -d2

  • 0 in reply to Don Dapkus
    Prodigy 90 points

    Hi Don,

    Thanks.  I should explain my application a little more.  It's not really an audio application.  I'm really only using this for the PGA function because it offers fine enough steps for my application (almost everything I have found come in binary or scope gains, or are optimized for RF...and draw a lot of power).  I'll only be needing to apply between -6/+3dB, but need as many steps between as I can get (I'd prefer a little finer than 1.5dB...but it will do).  As such, I could potentially be running near the rails at some point in the signal chain (although never closer than 0.5V to the rails on the input, so I should be good there).  I won't be driving a low impedance load (this will be placed between a ~10kHz sine source and a fixed gain coil driver with high input impedance), so I think my only concern will be where the output driver clips (or if there is anything internal that limits headroom).  Can I assume 0.5V for the output as well...even when driving a high impedance? 

    Paul