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UCC28070: when Tj is larger than 125C and lower than 160C, does UCC28070 shut down?

Max Han
Intellectual 2260 points
Part Number: UCC28070

Hi

customer do extreme test in their product, they find when UCC28070 case temperature is 120C, UCC28070 will shut down.

in datasheet, It shows that when UCC28070 Tj is higher than 160C, chip will shut down.

1. so customer want to know the 160C accuracy, they want to know if UCC28070 will shut down when Tj is in the range of 125C and 160C?

2. when Tj is higher than 125C, the parameter data may be out of range, so customer want to know, when Tj is in the range of 125C and 160C, is there any risk that their circuit damage or PFC circuit has some issue?

thanks.

  • 0
    TI__Mastermind 31580 points

    Hi Max,

    I will check to see if we have data on the thermal shutdown parameter but from previous experience on other devices I think  it will be much higher than 125C. From reading the datasheet the Tj needs to be over 160C for the thermal shutdown to operate.

    Thermal shutdown should not occur if the Tj is close to 120C.

    We have to respect the datasheet information if it states that the ABS max limit is 125C, however I think the risk of damage is low between 125C and 150C.

    If the UCC28070 shuts down at a case temperature of 120C, the junction temperature will be higher, does the customer know how much power is been dissipated in the IC ? They can measure the current on Vcc and work out the internal temperature rise of the Tj compared to the case temperature.

    Is it possible that the UCC28070 is shutting down for some other reason like Vcc rail dropping ?

    Regards

    Peter

  • 0 in reply to Peter Meaney
    TI__Mastermind 31580 points

    Hi

    Just to let you know that I am still requesting more data on the OTP setpoint. I hope to have an update later this week.

    Regards

    Peter

  • 0 in reply to Peter Meaney
    TI__Mastermind 31580 points

    Hi Max,

    TI has limited data that indicates Tj shutdown about 165C on bench samples. A +/- 10C is a reasonable estimate on variance around the 165C value. During design TI would have made sure that the turn-off (Tj rising) threshold would always be > 125C.

    Regards

    Peter