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LM25122QPWPTQ1

Nagaraj R63
Prodigy 200 points
Other Parts Discussed in Thread: LM5122

Dear  All

Please find the attached  my schematic for your review , This design is going to Automotive industry  Infotainment , Pls review Input protections and Booster converter outputs and provide me your comments

Regards 

Nagaraj R

SCHEMATIC1 _ Main PWR.pdf 

  • 0
    TI__Mastermind 21720 points
    Hi Nagaraj,

    Thank you for reaching out to us with your question.

    Can you please provide the following application information so we can complete the review?

    VIN range: (Minimum and Maximum values)
    VOUT:
    IOUTmax:
    Switching frequency:

    Thanks,

    Garrett
  • 0 in reply to Garrett Roecker
    Prodigy 200 points
    Hi Garrett

    Vin minimum 8 V , Maximum 18V
    Vout :8.2V ,
    Switching frequency 150Khz
  • 0 in reply to Nagaraj R63
    TI__Mastermind 21720 points

    Hi Nagaraj,

    Since the input voltage is above and below the target output voltage are you looking for a buck-boost converter? Otherwise the boost converter will only be active when VIN <8.2V, and the rest of the time the output voltage will just be equal to the input voltage. Here is a reference design with the LM5122 configured as a SEPIC (buck-boost) regulator.

    Also what is the maximum output current?

    Thanks,

    Garrett

  • 0 in reply to Garrett Roecker
    Prodigy 200 points
    Hi Garrett

    Yes , We need booster operation , Battery goes below 8 V , Our device still on . If battery above 8V booster should operate bypass mode .
    Please give me your comment when battery goes below 8V booster should alive with out issues .

    Please check booster mosft & Inductor, FB resistor values . frequency ... comments

    Regards
    Nagaraj R
  • 0 in reply to Nagaraj R63
    TI__Mastermind 21720 points
    Nagaraj,

    To check the design I need to know the maximum output current. Can you please provide this?
    Also I want to confirm that the minimum input voltage is 8V. Based on the UVLO resistor, the turn off voltage of the device is around 4.1V. Please confirm the minimum input voltage

    -Garrett
  • 0 in reply to Garrett Roecker
    Prodigy 200 points
    Garrett,

    Maximum current is 4A

    Battery minimum voltage is 8V ,

    Crank cold start voltage we kept 4.5 voltage is minimum / Booster will operate only Crank cold start mode only , rest of the time device will be bypass mode

    Regard
    Nagaraj
  • 0 in reply to Nagaraj R63
    TI__Mastermind 21720 points
    Hi Nagaraj,

    Please see my comments below.

    1. Set the current sense resistor to 6mOhm (R2)
    -This will keep the selected inductor for exceeding the saturation current during normal operation.

    2.SLOPE PIN resistor R10
    -Set this to 200kOhm.

    3. Bottom feedback resistor (R14)
    -This should be approximately 8.7kOhm to set the output voltage at 8.2V

    4. Compensation
    -Recommend changing the value of the follow components to improve the gain margin.
    R12= 25kOhm
    C13 =6.8nF
    C15 =330pF

    Please let me know if you have any questions.

    Thanks,

    Garrett