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TPS536C7: Max voltage compensation

Eliot Gentet
Prodigy 90 points
Part Number: TPS536C7

Tool/software:

Hi,

Is there any maximum voltage drop that can be compensated by the sense line of the TPS536C7B1 ?

Regards,

Eliot

  • 0
    TI__Expert 5825 points

    Hi Eliot, 

    Theoretically, yes, however the voltage droop compensation from the control loop will depend on the power delivery network of the board, characteristics of the layout of the controller and powerstages, and the control loop settings used by the TPS536C7 to regulate output voltage during the load transient that causes the droop.

    There is no easy way to calculate this, however one guideline you can follow is the maximum voltage ripple specification of the compute device you're powering, most of the large compute semi designers in the market have some specifications published. The TPS536C7 has succeeded in powering all the major compute brands that come to one's mind.  If you're using a bespoke or less common compute device, we can take the conversation offline to email for us to evaluate if we can fit your application. 

    Kind regards,
    Nick Z

  • 0 in reply to Nick Zahabizadeh
    Prodigy 90 points

    Hi Nick,

    Thanks for your feedback.

    In my case I was taking about a constant current that generates a voltage drop in the PCB.
    If we imagine that the power loss in the PCB that is induced by the voltage drop is taken care of (the PCB is cooldown by water cooling, for example).

    What would be the maximum voltage drop that can be compensated by the TPS ?

    For example if there is a 300 mV continues drop on the PCB, can the TPS compensate ?
    So if we want to have 1.1 V at the load, the TPS would have to compensate for the drop by outputting 1.4 V.
    In that case, of course, the sense line is connected close to the load.

    Thanks.

    Regards,

    Eliot

  • 0 in reply to Eliot Gentet
    TI__Expert 5825 points

    Hi Eliot, 

    To make sure I'm understanding your question correctly:

    • Assume the load needs to be supplied at 1.1V.
    • Due to various impedances on the board, there is a 300mV drop from the output of the powerstage/inductors to the load supply input.
    • The load needs to remain supplied at 1.1V. 

    In this scenario, yes we can power the load. The controller uses voltage sense lines to detect when the output voltage (load's input) is falling below the 1.1V output voltage target, and will start increasing the PWM duty cycle going to the powerstages to ensure the output voltage remains up at 1.1V. The controller will continue to attempt to raise the output voltage sensed by the sense lines equal the digitally-set target output voltage.

    Again, it's sort hard to deterministically calculate the behaviour of the controller. How fast does the 300mV drop occur? If it's losses across the board, then that should be fine. If sudden load transients cause the 300mV drop within a couple nanoseconds, then that's a very different discussion about our controller's ability to keep the load supply at target. 

    Also, a brief disclaimer that we highly recommend the powerstages and inductors should be placed as close to the load as possible to reduce losses. 

    Kind regards,
    Nick Z