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LM2673

amara bassem
Prodigy 10 points
Other Parts Discussed in Thread: LM2673

Hi Sir.

I am AMARA BASSAM from Renault Group company.

We need to design a board to convert 12V to 5V 3A

I share with you the schématic of this block

After test of this shcématic we find that the output voltage is all time in 10V

  • 0
    TI__Mastermind 27040 points

    HI

    can I know which input you add in your circuit  and when output all time in 10V, what is your feedback resistor value and what is the FB voltage? 

    Thanks

  • 0 in reply to Daniel Li14
    Prodigy 10 points

    Hi Mister daniel.

    Firt i think you for your quiqly answer.

    the input is 12V.

    the target is to convert input power 12V to 5V 3A.

    The resistance in the pin 5 of LM2673 is 4.99 Ohm.

    in the Feedback pin we have to resistor R1 and R2 1K Ohm.

    I share the schématic of this small board

    Thank you.

    .

  • 0 in reply to amara bassem
    TI__Mastermind 27040 points

    HI 

    if you use adj version of LM2673, with 1K ohm up and down feedback resistor, you should get 2.4V output voltage because internal Vref of adj version is 1.2V . Can you check the FB voltage, and make sure it is output adjustable version instead of fixed output version.

    I think PIN 5 resistor is  4.99kohm instead of 4.99ohm, right? 

  • 0 in reply to Daniel Li14
    Prodigy 10 points

    Hi mister Daniel

    i replace the R2 value by 3.3K ohm in pin 5 it is 4.99 Kohm

    and i find this value of volatage pins

    Pin 1 :  10.5V

    Pin 2 :  12V

    Pin 3 :  11.6V

    Pin 4 :  0V

    Pin 5 :  1.19V

    Pin 6 :  0.00036V

    Pin 7 :  4.36V

    Thank you.

  • 0 in reply to amara bassem
    TI__Mastermind 27040 points

    HI

    Do you have output voltage? it looks you have voltage at PIN1 but no voltage at PIN 6, is there any connection or soldering issue?

    Cause if PIN1 is 10.5V, Vo should have voltage around 10.5V, but FB(PIN 6)  will sense the voltage by  dvivide resistors ,it should have the votlage, based on your divide resistor,it should have around 1.75V 

    Thanks