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LMR51420: Thermal Resistance and Current Limit

Kazuki Itoh
Genius 10710 points
Part Number: LMR51420

Tool/software:

Hi team,

Could you support inquiries below?

Thermal Resistance RθJA

The IC ThetaJA Effective displayed in the WEBENCH® Power Designer differs from the RθJA specified in the datasheet. What conditions were used to determine this value?

High-Side/Low-Side Current Limit

The temperature characteristics in Figure 7-10. HS and LS Current Limit vs Temperature of the datasheet differ from the high-side/low-side current limit values in 7.5 Electrical Characteristics.

How should these be interpreted? (I understand the 25°C value on the horizontal axis of Figure 7-10 matches the value in 7.5 Electrical Characteristics.)

Best regards,

Kazuki Itoh

  • 0
    TI__Mastermind 22060 points

    Hi Itoh,

    The thermal resistance for the IC in Webench is typically based on a measurement taken on the EVM and is more representative of a real application. The Table 7.4 is based on the JEDEC simulation standard for comparative purposes only. 

    Use the Webench value for this design.

    For the current limit curve, that is a typical device curve to show how the current limit may change over temperature.

    The EC limits represent the minimum and maximum values.

    Best regards,

    Ridge