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PMICLOADBOARDEVM: Turn on Sequence of LOAD BOARD

NITHYADAS P V
Prodigy 30 points
Part Number: PMICLOADBOARDEVM

Sir,

The mosfet in my load board got damaged. I would like to know the turn on sequence of the board, that is +/- 11 V , control signal and output voltage of channels .

Nithyadas

  • +1
    TI__Expert 6440 points

    Hi Nithyadas,

    Yes, sequence is that first supply +-11 V, then control signal but keep state low. After that connect wanted voltage rail to output and then turn control on.

    I would say that it is quite rare to break down mosfet. Loading DC with too long duty can cause excessive heating and damage mosfet but otherwise design is very robust.

    In what situation your mosfet broke down?

    BR, Jari

  • 0 in reply to Jari Niemela13
    Prodigy 30 points

    Sir,

    I gave 250 mV control signal continuous for measuring 5A load . Output voltage was 2 V.I want to use this board as load for a synchronous buck converter.

    Is it only used for transient response analysis?

    Nithyadas

  • +1 in reply to NITHYADAS P V
    TI__Expert 6440 points

    Hi Nithyadas,

    This board is designed for transient load waveform generation focus on fast rise/fall times. Of course it can handle some level of DC loading as well but 10W continuous load is quite high already for this board. We have used power resistors to add DC load if we have wanted to have continuous DC loading and some load transient top of that.

    BR, Jari

  • +1 in reply to Jari Niemela13
    Prodigy 30 points

    sir

    My application is pol synchronous buck converter of 48-1v with 30 W power rating. So this cannot be used as a constant load as per my understanding from our discussion. So could u suggest any method for testing this converter. Also what is the maximum duty ratio of loa transients that can be applied.

  • +1 in reply to NITHYADAS P V
    TI__Expert 6440 points

    Hi Nithyadas,

    This load board is for load transient testing and not the best solution for DC load testing. We usually use for DC loading active load array devices and/or source meter unit (SMU) to sink load current.

    Idea is to keep duty ratio at a level that load board is not heating too much. Many times for example 1/100 is sufficient.

    BR, Jari

  • 0 in reply to Jari Niemela13
    Prodigy 30 points

    Sir,

    One more question what is the minimum on duration possible. What is the maximum power the load board can carry?

  • 0 in reply to NITHYADAS P V
    TI__Expert 6440 points

    Hi Nithyadas,

    Minimum pulse duration is dependent on rise/fall times. We have achieved 80ns rise/fall time up to 8A load current. This means minimum pulse for can be less than 200ns with this load level.

    Limiting factor is mosfet power dissipation which depends on temperature of the mosfet. If we take worst case on 70 degrees at Ta 70 C we can handle only 2W. With low enough duty cycle load can be quite high still if off cycle is long enough and average power dissipation is not exceeding mosfet limits.

    BR, Jari