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TPS53819A TINA Simulation with 3.3V Output

Other Parts Discussed in Thread: TPS53819A

Starting with the TPS53819A reference simulation model, I changed the bottom feedback resistor from 10K to 2.23K in order to create a 3.3V output. I also changed the load resistor from 60m-Ohms to 600m-Ohms. The simulation overshoots the output voltage to 4.0V and then shuts down without ever regulating. The voltage on the FB pin exceeds 600mV, but the SW node keeps switching. Can anyone tell me what the issue is?

I also tried increasing the inductor to 2.2uH in case there was a current ripple issue, and also increased output caps but without success - the output always overshoots and then shuts down.

thanks,

Lance

  • Lance,

    I am guessing that the RTRIP value is too high when you changed to the 3.3V output. I have run the simulation with RFBL=2.05k and RTRIP=15k. You values may be slightly different as I have estimated a lot of the design information and am not sure what your real design looks like. I get 3.3V out with the 600m load. You may want to add ESR to the output caps and ESL to the inductor (sorry, forgot your previous post... my bad) If you adjust the frequency (FRES_SEL variable), don't forget to use the table in the datasheet to update the RC time constant in the equations.

    I also had to extend the simulation time to 800us to get the Power Good signal for a little longer...