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How to Adjust the Output Voltage in LM43600PWP Board?

Omar Aldosari
Prodigy 20 points
Other Parts Discussed in Thread: LM43600

I'm using LM43600PWP evaluation board to step down my output voltage. The input voltage is expected to be something between 4-12 DC volts, and the output voltage should be 3.3V. The output of this buck converter is feeding a load of V(load)= 3.3V and I(load)= 13.33x10^6 A. I've seen some equations to adjust the output voltage in LM43600 datasheet; however, I'm I don't know how I can apply those equations to the LM43600 , that is inside the evaluation board LM43600PWP ? Where to start? And are there any any commanded tools or any preferred programmable language?  Thanks in advance.

Omar

  • 0
    TI__Genius 15810 points
    Hello,
    There is no programming required to use the LM43600 evaluation board. The evaluation boards have two resistors that set the output voltage namely RFBT and RFBB. Changing these according to the results of the equations in the datasheet will allow you to change the output voltage. In fact the evaluation board comes with a jumper 'J1' which allows the user to change between two output voltages. With the header for the jumper out, the default output voltage is 3.3 V. With the header of the jumper in, the output voltage is 5 V.

    You mentioned that the load voltage is 3.3V and the current is 13.33*10^6 A? Do you actually mean 13 million Amps? Or are you missing a '-' sign? Just asking.

    Regards,
    Akshay
  • 0 in reply to Akshay Mehta
    Prodigy 20 points
    Hi Akshay,

    Sorry I meant the load current is 13.33*10^-6 A, I was missing the '-' sign. I left the header jumper (J1) out, and I applied input voltage of 6 volt, and I received 3.5 volt out, I just don't want to exceed 3.3 volt. Besides, I seen these equations that you suggested in the datasheet. but how would I change RFBT and RFBB since they're already soldered in the board?

    Thanks,
    Omar
  • 0 in reply to Omar Aldosari
    TI__Genius 11085 points
    The output voltage is slightly higher than regulation when there's no load or very light load at the output. If there's load current at the output, the output voltage should be 3.3V. To change the divider, please desolder the resistor on the board and solder on the new one.
    -Yang
  • 0 in reply to Omar Aldosari
    TI__Genius 15810 points
    Hi Omar,
    As Yang mentioned, this device has a different low power mode that gets activated when the load current is very small. If you're okay then you could add a 'dummy' load at the output in form of a fixed resistor between VOUT and GROUND and that would keep the output voltage at 3.3 V.
    Regards,
    Akshay