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UCD9248 & PTD08D210W - Vout Ramping up very slow

SIVASUNDARAGANESH V V
Prodigy 120 points
Other Parts Discussed in Thread: UCD9248, PTD08D210W

Hi, 

 I am powering my FPGA with the power module - UCD9248 & PTD08D210W.

I started working on one rail first - Rail 1 which is set to 1v. The Vout from PTD08D210W is ramping up very slow. i.e. it takes 30 mins to reach 1V. 

Can Anyone tell why it is ramping up very slow?.

Also, I noticed the status register showing output off . 

Please refer the attachment below,

   

Best Regards

Sivasundaraganesh V.V
65 9750 4742

  • 0
    TI__Genius 9845 points
    Hi Sivasundaraganesh,

    If it takes 30 mins to rise, the rail is not turned on. Please check "On/Off Config" under Configure tab. If it is CONTROL Only, you will need to toggle CONTROL line to turn on the rail (the CONTROL line window is shown in your screenshot.) If it is OPERATION Only, you will need to select "On" to send an OPERATION command (the OPERATION window is also shown in your screenshot). If it is "Always Convert", the rail should start as soon as Vin is above Vin_on threshold, which is configured under Configure->Iout,Vin,Temp Config->"Turn Controller On when Vin is Above:".

    Regards,
    Zhiyuan
  • 0 in reply to Zhiyuan Hu
    Prodigy 120 points
    Hi Zhiyuan,
    Thanks. Now its working after I change the ON/OFF config to operation Only and apply operation command.
    I have another doubt in "Turn Controller On when Vin is Above" -- I believe this refers to pin5 of UCD9248. Am I right?
    In KC705 eval board, the Vin is set to 2V (I checked it in the hardware by probing) but when I read back through the Fusion digital GUI, the "Turn Controller On when Vin is Above" parameter is set to 6V and the board is working fine. I have the similar configuration in my board but not working, the only difference is my main supply is 5V.kindly help me on this.

    Best Regards
    Sivasundaraganesh V.V
    65 9750 4742
  • 0 in reply to SIVASUNDARAGANESH V V
    TI__Genius 9845 points
    The Vin sense pin is Pin 5.

    2V is what you measured on Pin 5, correct? It is scaled down by a resistor divider. The resistor divider ratio is configured as Vin Scale under Other Config. So the device can calculate the real Vin value.

    If you apply 5V onto Pin5, it will damage the pin (above its absolute max). The ADC can only measure up to 2.5V. You need to scale down Vin and set Vin scale properly.

    Regards,
    Zhiyuan
  • 0 in reply to Zhiyuan Hu
    Prodigy 120 points

    Hi Zhiyuan,

     Thanks. I applied the voltage divider ratio to the Vin scale and it works fine now. yes, 2V is measured at the pin 5.

    Best Regards

    Sivasundaraganesh V.V