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TPSM843B22 TPSM843820 TPSM863257 TPSM33625 : Temperature De-rating

Justin Ayvazian
Prodigy 10 points
Part Number: TPSM843B22
Other Parts Discussed in Thread: TPSM843820, TPSM863257, TPSM33625

Tool/software:

We are seeking some guidance on temperature de-rating for the following components:

  • TPSM843B22
  • TPSM843820
  • TPSM863257
    • Specifically, any performance de-rating between Tj = 125C and Tj = 150C
  • TPSM33625
    • Any functional roll-off as you approach the 'max ambient' thresholds shown in Figs 8-5, 8-8, 8-11?

In short, would we expect to see any reduction in efficiency, maximum available current draw, or any other change in part behavior as we approach the junction temperature limits, or do these parts provide full specified power at the specified efficiency up until that thermal limit? Thanks in advance for your help.

  • 0
    TI__Mastermind 20830 points

    For the TPSM843B22 and TPSM843820, yes there will be derating and it will depend on the switching frequency, input voltage, output voltage and output current. 

    The operating area can be reduced for thermal or based on the input voltage, output voltage, switching frequency and ripple current.   

    The integrated inductor is a fixed value and there is a current limit threshold in high side and low side fet and a sinking current limit. 

    The input voltage, output voltage and switching frequency will give a ripple current.   

    Typically, Lower switching frequencies and higher output voltage have higher inductor ripple currents are limited based on the ripple. 

    Higher switching frequency will lower ripple but the higher switching frequency will increase power dissipation and reduced the operating temperature range. 

    If you know the operating conditions go the https://webench.ti.com/ tool and enter the part number and conditions and  hit submit.      Start with TPSM843B22, the TPSM843820 have a limited vout range