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TPS7A1601 / startup operation

Ryuji
Guru 20090 points

Other Parts Discussed in Thread: TPS7A1601EVM-046

Hello,

I have questions about TPS7A1601 startup operation.
<conditions>
VIn=50V
Vout=5V(default setting of EVM)
Iout = 0A( No load)
 
Please see the attached file as waveform.
 
<Questions>
(1) Is this operation no problem ?
(2) Please let me know this operation mechanism.
      If there is any application note, please let me know.
 
Best Regards,
Ryuji Asaka
 
  • 0
    TI__Guru 55940 points

    Hi Ryuji,

    Would it be possible to provide a schematic?  This will help in understanding what is occurring in your application.

    Very Respectfully,

    Ryan

  • 0 in reply to Ryan Eslinger
    Guru 20090 points

    Hello Ryan san,

    Schematic is same with  TPS7A1601EVM-046.
    If you neef more information, please let me know.
     
    Best Regards,
    Ryuji Asaka
  • 0 in reply to Ryuji
    TI__Guru 55940 points

    Hi Ryuji san,

    I am trying to replicate the waveforms.  Did you make any modifications to the EVM?  Also, what is the status of J5, J6?  Is C3 populated?

    Very Respectfully,

    Ryan

  • 0 in reply to Ryan Eslinger
    Guru 20090 points

    Hello Ryan san,

    I checked customer's information.
    ----------------
    -They didn't any modification to the EVM. All parts are same with EVM.
    -C3 is not populated
    -J5 is open
    -J6 is short
    -instruments
       Programable Power Supply :  TR6143 , Advantest
      Oscilloscope : TDS3014C , Tektronix
      Probe : P6139B , Tektronix
    ----------------
    If you need more information please let me know.
     
    Best Regards,
    Ryuji Asaka
  • 0 in reply to Ryuji
    TI__Guru 55940 points

    Hi Ryuji san,

    I am unable to duplicate your waveform on the bench.  I would suggest having the customer try a new EVM.

    Very Respectfully,

    Ryan

  • 0 in reply to Ryan Eslinger
    Guru 20090 points

    Hello Ryan san,

    Thank you for the checking. I will replace the EVM.
    By the way,  is my waveform abnormal?
     
    Best Regards,
    Ryuji Asaka
  • 0 in reply to Ryuji
    TI__Guru 55940 points

    Hi Ryuji san,

    Yes.  Your waveform is unusual.  Typical startup waveforms will look like Figure 13 in the datasheet and Figure 1 in the EVM's User's Guide.

    Very Respectfully,

    Ryan

  • 0 in reply to Ryan Eslinger
    Guru 20090 points
    Hello Ryan san,
     
    Thank you for the checking.
    I will get the customer's EVM and check the customer's EVM.
    And I will get the new EVM and test it too.
     
    I will post again if I get new concern.
     
    Best Regards,
    Ryuji Asaka
  • 0 in reply to Ryuji
    Guru 20090 points
    Hello Ryan san,
     
    I get new inromation from the customer.
    Could you please kindly let me know the customer usage is acceptable or not.
     
    -EN is turned on from other power supply of Vin
     Then , they input 50V by hot-plug.
     Thus, their Vin tr is faster than Vout tr. (please see the attached file)
     
     
    I think that , cause of this 2 step start up sequence is  current limit or refference voltage problem or device failure due to hot-plug.
    Please kindly let me know the below.
     
    1. Can we use TPS7A1601-EVM by hot plug ?
    2. If Vin tr is fast, Vout seaqunce will be 2 step ?
        If yes, please let me know the reason.
     
    Best Regards,
    Ryuji Asaka
      
  • 0 in reply to Ryuji
    TI__Guru 55940 points

    Hi Ryuji san,

    From your latest post it appears that the customer is supplying the EN pin with a voltage before Vin.  This is not the way the device was designed to operate.  Ven should be less than or equal to Vin at all times.  Please see the page 5 of the datasheet (copied here for convenience).

    Very Respectfully,

    Ryan

  • 0 in reply to Ryan Eslinger
    Guru 20090 points
    Hello Ryan san,
     
    Thank you for the information.
    I miss out this description... sorry.
    I see Absolute maximum ratings only...
     
    Best Regards,
    Ryuji Asaka