• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 63 subscribers
  • Views 80 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS54KC23: Temperature Derating Guidelines for TPS54KC23

歩 綿貫
Prodigy 30 points
Part Number: TPS54KC23

Tool/software:

Hi TI Team,

I'm designing a DCDC using the TPS54KC23 to output 1.2V at 25A.
However, this converter will be placed in an environment with an ambient temperature of around 70°C.

In this situation, I would like to know how we can estimate the heat dissipation in advance.
The datasheet does not include an SOA graph, so I am unsure how to verify whether this design is thermally safe before prototyping.

Could you please advise on the recommended method for thermal estimation or derating in such conditions?

Thank you in advance for your support.

Other Information:

Vin:12V, Air Flow: 50LFM, Fsw:1100kHz

  • +1
    TI__Genius 11396 points

    Hi,

    Since the TPS54KC23 datasheet does not provide an SOA or explicit derating curve, the best approach is to estimate thermal performance based on power loss calculations and the thermal metrics provided in the datasheet. 

    1. Estimate Power Losses

    • Use the TPS54KC23 efficiency curves at your operating conditions (Vin = 12V, Vout = 1.2V, Iout = 25A, Fsw = 1100kHz). 
    • TI's WEBENCH Power Designer can help with loss and thermal estimates
      • Using WEBENCH, I got somewhere between 5~5.5W for IC power dissipation

    2. Translate to Junction Temperature

    • Use the thermal resistance values from the datasheet (RθJA=13.2°C/W measured on 6-layer EVM layout))
    • Estimate the junction temperature: TJ = Tambient + (Ploss x RθJA)
      • Based on 5~5.5W from Step 1, I got TJ between 136°C and 142.6°C.

    3. Derating / Safety Margin

    • Compare the calculated TJ with the maximum recommended operating junction temperature, which is 125°C for this device (absolute maximum is 150°C).
    • If your estimated junction temperature is uncomfortably close to the limit, consider reducing load current, lowering switching frequency, or improving cooling (higher airflow, larger copper area, thermal vias, etc.). Using external VCC will also help improve efficiency and reduce power loss.

    4. Verification

    • For final validation, thermal measurements on the actual PCB are strongly recommended, as layout and copper area have significant impact. 

    Thank you,
    Tomoya

  • 0 in reply to Tomoya Ide
    Prodigy 30 points

    Hi,

    I will proceed with power calculations using WEBENCH and calculations based on the Rθja@EVB.

    Additionally, I plan to conduct a preliminary evaluation using the EVB.

    Thank you for your advice.