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THS3470: Datasheet Clarification

Abigail Leonardi
Expert 3510 points
Part Number: THS3470
Other Parts Discussed in Thread: THS3120

Tool/software:

Hi,

In the figure on page 12 of the datasheet, RFB_TRACE is shown in the Vout path.  However, the parameter section (page 6) defines RFB_TRACE as "Internal trace resistance to feedback pin."  The latter makes more sense.  Is the figure incorrect?

 

The standby quiescent current is specified as 12.6mA.  I would expect it to be much less.  (For example, the THS3120's standby quiescent current is 0.5mA.)  Is this correct?

  • 0
    TI__Genius 16575 points

    Hi Abigail,

    That is correct I believe this should be FB; therefore, the figure is incorrect. I will bring this up to our systems engineer and should have this corrected. For the standby current, a lot of the values in the datasheet will be adjusted for the final datasheet release but I believe this quiescent current value is going to be in this range. There is a lot of additional circuitry in this device compared to some of our other current feedback devices as well larger transistors to drive the large current outputs of this device, which would draw a lot more current even in standby mode. 

    Best Regards,

    Ignacio

  • 0 in reply to Ignacio Vazquez Lam1
    TI__Expert 3510 points

    Thanks Ignacio!

    Additional clarification, The "Headroom to either supply" parameter of 5V seems high (on page 7).  Similar op amps require much less.  Is this correct?

    And how long does it take for the device to recover from standby?

  • 0 in reply to Abigail Leonardi
    TI__Genius 16575 points

    Hi Abigail,

    Yes the headroom is going to remain around 5V to either supply. For your second question, this is something I believe has not been captured but I can bring this up to our systems team to see if this is something we could look into for the final release of this device. Just to confirm is the customer wondering how long the device takes to fully settle when switching from standby mode to full bias mode?

    Best Regards,

    Ignacio

  • 0 in reply to Ignacio Vazquez Lam1
    Prodigy 120 points

    Hi Ignacio,

    I would like to know the settling time when switching from standby mode to a non-standby mode.

    Also, which parameters change with the different power and bias modes?

    Thanks,
    Andy

  • 0 in reply to Andy Bartfay
    TI__Genius 16575 points

    Hi Andy,

    We plan on adding this specification to the final datasheet but we expect the time to be around 20us from disabled (power down) to full bias. The final value may change as we test different parameters. As far as parameters that change for different bias modes, we can expect ac specs such as bandwidth, slew rate, and distortion performance to be affected along with the quiescent current of the device. The final datasheet is expected to show how these different bias mode affect some of the device parameters I mentioned. 

    Best Regards,

    Ignacio

  • 0 in reply to Ignacio Vazquez Lam1
    Prodigy 120 points

    Ignacio,

    Thanks!

    Andy