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TINA-TI: LMH6554 switched cap load simulation issue

Fede Bes
Prodigy 10 points
Part Number: TINA-TI
Other Parts Discussed in Thread: LMH6554

Tool/software:

Hi, I am trying to simulate the behavior of LMH6554 while driving a switched capacitor load (red circled). You can see the switches parameters. The nets Vop and Vom saturate although the input is a sine wave.

What makes me suspect a simulation issue with the switches is the fact that if I remove them from the schematic and just directly connect the cap load in a continuous time manner, Vop and Vom follow the input as expected. Is there anything wrong with the way the switch is set up? Should I use a different kind of switch? 

4743.LMH6554.TSC

Thanks

  • 0
    Prodigy 10 points

    I noticed that if I elongate the period and sampling time (3.125us and 12.5us) by x1000 the output does come out as expected. However the LMH6554 response is way faster than the 3.125ns, which are allocated in the first test for sampling (switches ON) therefore I suspect there is some issue with a model. Can anyone from TI confirm please? We are not sure whether we should proceed with the part order if we cannot make sure first this is simply a simulation issue

    Transient result with the actual sampling time of 3.125ns showing VtopP and VtopM saturation. (Again VtopP and VtopM follow the input as expected when sampling time is 3.125us which does not make sense to me)