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LM61480T-Q1: 12Vin-3.3Vout/4A, 3.3Vin-1Vout/5A

Rama Prasad
Prodigy 125 points
Part Number: LM61480T-Q1

Tool/software:

Subject: Clarification and Recommendation for Buck Converter Selection

Hi TI Team,

I would like to standardize the buck converter for my Ethernet switch application with the following requirements:

  • Input/Output Requirements:
    • 12V input to 3.3V output at 4A.
    • 3.3V input to 1V output at 5A.

I found the LM61480T-Q1 to be a good option in terms of thermal performance. The maximum temperature I want to allow at full load is 45°C.

However, I noticed a discrepancy regarding the minimum input voltage:

  • The datasheet specifies a minimum input voltage of 3V,
  • While Webench recommends a minimum of 3.6V. (screenshot below FYR)

Could you please clarify this discrepancy?

Additionally, could you suggest a better alternative for achieving a 1V/5A output with an IC junction temperature of 45°C at full load, while ensuring better EMI performance?

Looking forward to your response.



  • 0
    TI__Mastermind 24115 points

    Hi Rama, 

    Here is a note from the datasheet underneath the recommended operating conditions to explain that discrepancy:

    Webench is meant to emulate conditions similar to this minimum operating input voltage specification. 

    The best way to achieve 1 Vout with this device is by populating RFBT with an appropriate resistor (10K is usually enough) and leaving RFBB open. This device should work for your operating conditions.

    Thank you,

    Joshua Austria