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TPS546C20A: How to calculate the inductor value at a wide output range?

Ricardo_Li
Intellectual 260 points
Part Number: TPS546C23
Other Parts Discussed in Thread: TINA-TI

Hi Teams.

I'm looking for a power supply solution. The request is: 0.8V to 4V output voltage(adjustable), 12V input voltage, 60A output current. 

The output voltage of TPS546C23 can catch up 0.35V to 5.5V. I can add a multiplexer to change FB Resistor Divider Ratio. While, I don't know is it stable at the whole output range when the value of inductor was fixed. If it is stable, can you help me calculate the value of inductor?

Regards,

Ricardo

  • 0
    TI__Genius 14455 points

    Hi Ricardo,

         Can you please let us know what is the application that is driving this use case?

          For a fixed inductor, for your given input output  conditions, as you increase the output voltage the inductor ripple current would increase. So you can design the for maximum Vout case and then try using the same inductor for minimum Vout case.  

          Regarding stability and other things to be considered, you will have to verify the design with simulations across a wide range of operating conditions to get confidence before you prototype.

    Given that your requirement is 60A, I am assuming you are planning to stack these converters. Is that correct?

    Regards,

    Gerold

  • 0 in reply to Gerold Dhanabalan - Online Design Tools
    Intellectual 260 points

    Hi Gerold,

    That's for a Burn In tester. There have more than 200 hundreds DUTs (Device Under Test). We need test the devices under their recommended operating conditions (0.8V to 4V).  The total power supply would get up to 200A. So we will splitting the board to 4 parts. Every part will provide 60A current (0.8V to 4V). The remote sense is also necessary. Two TPS546C23 devices can be paralleled together to provide 60A load.

    Using WEBENCH, I get a TINA simulation file. 

    The output voltage simulation result are as following:

    0.8V output

    4V output

    After a calculation, I get the the key component's value. Switching frequency was set to 500KHz. The minimum inductor value is 507nH (to cover 4V output). So I pick a 560nH inductor. Iripple is  9.5A. Under a 10A Load Transient, the minimum output capacitor is about 1400uF. Under a 50mV max voltage ripple, minimum output capacitor is 47uF. Max ESR is 0.96 mOhm. When output voltage exceed 1.5V, a RBIAS resistor should be added.

    While, I'm unable to simulate the dynamic output voltage from 0.8V to 4V using TINA. Do you have any idea to evaluate the dynamic output voltage?

    Is there any problem under this configuration? Please let me know if you have a better idea.

    Here is the simulation file.

    Best Regards,

    Ricardo

    TPS546C23.zip

  • 0 in reply to Ricardo_Li
    TI__Genius 14455 points

    Hi Ricardo,

        You can simulate the dynamic configuration in TINA-TI by using a switch to connect the appropriate feedback divider network. 

    Can you try that?

    Regards,

    Gerold

  • 0 in reply to Gerold Dhanabalan - Online Design Tools
    TI__Intellectual 1040 points

    Hi Ricardo,

    Please let us know if you still need any help from us otherwise, we are going to close out this thread.

    Thanks,

    Somen

  • 0 in reply to Somen Das
    Intellectual 260 points

    Hi Somen,

    You can closed this thread now. Thank you.

    Regards,

    Ricardo