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UCC25800-Q1: Adding an external thermal protection circuit

Taroimo
Intellectual 680 points
Part Number: UCC25800-Q1
Other Parts Discussed in Thread: UCC25800

Tool/software:

Dear TI team

 

I would like to confirm something about the UCC25800-Q1.

I am considering adding an external circuit to protect this device from overheating.

 

The DIS/FLT terminal has the function of stopping the IC's operation by receiving a disable signal from an external source,

so I think that by connecting this terminal to GND when the temperature rises, I can stop the IC's operation.

I also think it would be possible to design it so that it automatically returns to normal by setting it to "high" again when the temperature drops again.

 

Is my understanding above correct?

Also, please let me know if there are any other points I should be careful of.

 

Best Regards,

Taroimo

  • +1
    TI__Genius 15566 points

    Taroimo,

    UCC25800 has TSD (Thermal Shutdown) protection which can be monitored at the DIS/FLT pin. The way how the protection works is that an internal current source pulls down this pin through an internal supply VREG with a 100kohm resistor (see picture below from DS) connected. This happens when a fault is triggered. In the case of TSD, when the junction temperature Tj reaches 160C. Then, the device will try to release the fault after 100ms since the fault was triggered and it is required that Tj is below 160C-Hysterisis.

    Nothing is required to be connected externally for this to happen, you can let the DIS/FLT floating. DS recommends, to prevent noise coupling through this pin, connecting this pin to a 3.3V/5V external supply (which can be VERF pin) through a pull up resistor (check picture below from DS).

    Thank you

  • 0 in reply to Manuel Alva Hernandez
    Intellectual 680 points

    Hi, Manuel

     

    We have inquired about the background of the customer’s question.

    This time, they want to apply thermal protection at a temperature lower than the internal TSD.

     

    Therefore, I would like to ask the following question:

    The DIS/FLT terminal has a function to stop the operation of the IC by receiving a disable signal from an external source.

    Therefore, I believe that by pulling down this terminal and connecting it to GND when the temperature rises,

    the operation of the IC can be stopped. Additionally, I think it is possible to design it to automatically return to normal by setting it to “high” again when the temperature drops.

     

    Is it correct to assume that this usage is acceptable?

     

    Best Regards,

    Taroimo

  • 0 in reply to Taroimo
    TI__Genius 15566 points

    Hi Taroimo,

    That thinking explained above is correct.

    Thank you.