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TPS54623: Unable to optimise the Maximum overshoot Settling Time.

MANISH KOTNI
Prodigy 85 points
Part Number: TPS54623
Other Parts Discussed in Thread: TPS54218, TPS54318, TPS54319, TPS54320, TPS54418, TPS54521, TPS54618, TPS54620, TPS54622, TPS548B22, TPS548C26, , TPS548D22, TPS53355, TPS546D24A, TPS548D21

Hi Ti Team,

We are using the part TPS54623RHLR for the below mentioned speciation's :

VOUT = 1.8 V
Rise Time = 10 ms
Monotonicity = 0 mV
Slope = 7120 V/s
Tolerance = +/- 10%
Ripple = 20 mV
Overshoot = 50 mV
Overshoot settling time = 0.05 ms
Iout = 0.56 A

we have tried many ways to optimise the Overshoot Settling time but we could optimise, kindly share your valuable inputs to optimise the Overshoot Settling Time.
for this design the desired Overshoot Settling time 0.05ms we could optimise upto 0.36ms.


Master key : 0F0F4E54B4813362[v1] 

  • 0
    TI__Intellectual 2998 points

    Hi Manish,

    For fast transient response you will need modify the compensation components which in this case would be Rcomp, Ccomp, and Ccomp2. It would help to use type 3 frequency compensation instead of type 2. More details on type of compensations types can be found on our app note: https://www.ti.com/lit/an/slva352a/slva352a.pdf. In addition, I have attached the TPS54XXX calculator to use for COMP pin calculations.

    TPS54620_TPS54XXX_App Note_calculator_Ver5p0.xls

    Regards, 

    Eileen

  • 0 in reply to Eileen Hernandez Hernandez
    Prodigy 85 points

    Hi Elleen,

    Thanks for your response, Kindly confirm that the APP Note Calculator can support TPS54623RHLR. Over in the Excel sheet it was mentioned that this file supports the Below mentioned parts only.

    TPS54218
    TPS54318
    TPS54319
    TPS54320
    TPS54418
    TPS54521
    TPS54618
    TPS54620
    TPS54622
  • 0 in reply to MANISH KOTNI
    TI__Intellectual 2998 points

    Hi Manish,

    The calculator has similar parts like TPS54622 and TPS54620 that could be referred to although not exactly the same. Reaching a 0.05ms OS settling time is very hard to achieve. I have ran Webench on my side and some of the changes you could do to reach an overshoot settling time closer to 0.05ms include: increasing Rcomp, Ccomp, Ccomp2 as well as decreasing the pulse current source fall time. 

    Because this alters the compensation, there's tradeoff in stability so make sure to check it's still inside your desired parameters.

    Regards,

    Eileen

  • 0 in reply to Eileen Hernandez Hernandez
    Prodigy 85 points

    Hi Eileen,

    Thanks for your time & comments.
    I to ran a couple of simulation in webench by increasing the Compensation Parts, as you said its very hard to achieve as my Speciation OS Settling Time is 0.05ms i could achieve upto 0.24ms. Hence i conclude that its very hard to achieve the Specification.

    Could you please recommend the parts from TI where i can achieve these specs : 

    Input Voltage :1.8V
    (SVR)
    Digital supply

    0.56A

    Rise Time

    Time from 10% to 90% mark.

    10 ms

    Monotonicity

    Voltage dip allowed in ramp.

    0 mV

    Slope

    Ramp rate at any given time between 10% and 90%
    Max: 0.8*V(max)/rise time(min)

    7120 V/s

    Operational Range

    Voltage range for normal operating conditions (±10%).

    1.98 V

    Ripple

    Maximum Voltage ripple (peak-to-peak)

    20mV

    Overshoot

    Maximum overshoot allowed

    50mV

    Overshoot settling time

    Maximum overshoot allowed duration.
    (at that time delta voltage should be lower than the 5 mV from
    Steady state voltage)

    0.05 ms

    Please let me know if you have any more questions for me.

  • 0 in reply to MANISH KOTNI
    TI__Intellectual 2998 points

    Hi Manish,

    Yes, that sounds close to the value I was getting on my simulations.

    You can use our Webench search tool to find parts following specific specs/parameters through this link: https://webench.ti.com/power-designer/switching-regulator 

    Regards,

    Eileen

  • 0 in reply to Eileen Hernandez Hernandez
    Prodigy 85 points

    Hi Eileen,

    Thanks for your comment, i had checked & validated a quite a couple of products but it could reach or satisfy my speciation's hence i request you to suggest exact part here are my specifications below. 

    Vin : 11.5V to 12.5V DC
    Vout : 0.8V
    Iout (Nominal) : 20.6Amp
    Iout (Peak) : 22Amp
    Rise Time : 10 ms
    Monotonicity : 0 mV
    Slope : 7120 V/s
    Operational Range Voltage range for normal operating conditions (0.8V ±5%) : 0.84 V
    Ripple (Vp-p) : 20 mV
    Overshoot Voltage : 50mV
    Overshoot settling time "Maximum overshoot allowed duration.
    (at that time delta voltage should be lower than the 5 mV from
    Steady state voltage)" : 0.05 ms

  • +1 in reply to MANISH KOTNI
    TI__Intellectual 2998 points

    Hi Manish,

    My expertise is on devices under 10A, the device you were initially testing TPS54623 has Iout (max) = 6A. Per your specifications, it looks like you are looking at a higher current rating (+21A) device. From some initial search it looks like this devices may fit some of the basic specs on the list: TPS53355, TPS546D24A, TPS548C26, TPS548B22, TPS548D22, TPS548D21.

    You will need to contact the teams who support those parts to see if they can help you further optimize the part to your specifications above. You can do this by posting a new E2E with the part you've selected. 

    Regards,

    Eileen

  • 0 in reply to Eileen Hernandez Hernandez
    Prodigy 85 points

    Hi Eileen,

    Thanks for your valuable comments, I will raise another question e2e regarding the new requirements.