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ALM2403-Q1: Thermal resistance and performance inquiry

Manu Chang
Expert 3260 points

Part Number: ALM2403-Q1

Hi Expert,

My customers have some inquirry regarding the ALM2403-Q1's thermal resistance and performance as below:

  1. Do we have method to accurately estimate the junction temp of the device? Customers have used the equation of the thermal resistance and power dissipation to calculate the junction temp, but the result they calculated from the ambient temp and result from the board temp have very big difference, so they want to know how do we estimate the junction temp.
  2. For for the themal characteristic parameters, is it calculated by the board based on JEDEC stantard? Can we share how the JEDEC board looks like and configured regarding the thermal design?
  3. Customers use cases ambient temp is relatively high (around 85-100C) and the power dissipation of the ALM2403-Q1 they evlauated is also relatively high (around 0.3-0.5W). So they want to know, do we have any data/info that under how much junction temp can ALM2403-Q1 continuously working without damage? Have we done such tests?

BR,

Manu

  • 0
    TI__Genius 17936 points

    Hey Manu,

    Good questions. 

    To start, what are the measured temperatures the customer is seeing? Since this is a power pad device, the layout will have significant impact on the thermal performance of the system. PSI (JB) is my preferred method for calculating the junction temperature, but you are correct in that a customer board may not necessarily perform exactly like the JEDEC standard PCB. 

    Here is a great collection of information for how we spec thermal performance: Semiconductor and IC Package Thermal Metrics .

    Section 5 of this document goes into detail for how this is measured, but know that this is effectively the same as theta JB for a package like this.

    The board is covered under JEDEC Standard JESD51-7, being a 1oz copper two layer PCB with 76.20 mm x 114.30 mm dimensions and copper planes with dimensions of 74.2mm x 74.2mm. 

    If the customer PCB is smaller area than this, you will see worse thermal performance. 

    HTOL is our standard lifetime test where we evaluate the mean time between failures for a certain mission profile. We have an FMEA document which covers this information in great detail:

    You can use our FIT rate calculator to easily calculate MTBF for any temperature you need. 

    https://www.ti.com/quality/docs/estimator.tsp

    Please let me know if you have any questions. 

    Best,

    Jacob