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TSC2007: TSC2007 Ramp-on/Ramp-off timing and appropriate switch

Steve Jarvis
Intellectual 600 points
Part Number: TSC2007

Hi,

According to TI App Note SBAA161 (link at the bottom), for the RSC2007 it is required to have precise Ramp-on as well as ramp-off timing.

Three questions (can you please answer each of them separately):

1) to implement the first suggested solution in that application note with the switch switching between GND and VDD, what is the preferred/recomended switch to use? Can you please provide one or more part numbers.

2) The ramp-on and ramp-off timing would obviously be affected by the size of bypass capacitor on the VDD pin. How do we ensure that the ramp-on and ramp-off timing is achieved? 

3) Because of point (2) above is the bypass capacitor better placed on the Vdd pin side of the switch or on the Rail side "before" the switch?

TI App. Note: http://www.ti.com/lit/an/sbaa161/sbaa161.pdf 

Many thanks

Rick

  • 0
    TI__Guru 63855 points

    Hello,

    1.)  Nearly any of TI's switches will work in this case.  Our team is not an expert at the most up-to-date switches so you may want to check with that team on the "Switches and Multiplexors" forum.  The product below looked interested based on a quick search we performed of their portfolio.

    http://www.ti.com/product/TPS22919

    2.)  Even with larger bypassing the min T_ON / T_OFF waveforms should be able to be met.  The minimum ramps are only 0.002V/us and 0.012V/us respectively in the more common "V/us" slew nomenclature.  0.1uF should be an effective decoupling/bypass capacitance located right on the VDD pin.

    3.)You should still place the bypass capacitor as close as possible to the VDD pin of the TSC2007.