TPS5120: About thermal shutdown

Hello Yusuke-san,

In a typical controller application it is the switching MOSFETs that get the hottest because they are in the power path. The TPS5120 being a controller generally dissipates the same amount of power regardless of load current. There is a curve of several parameters as a function of temperature shown on pages 17 and 18 of the data sheet. Two of these graphs illustrate the parameter tested up to 125 degrees C even though the data sheet rating of the product is just to 85 C. This shows that any over-temperature safety shutdown would occur above 125C. I know in the power IC regulators that thermal shutdown is set in the 150C to 165C range; but for a controller such as this I don't know of an established rule or typical value. If you want to actuate the thermal shutdown you can either heat the IC package with a large tip iron or heat gun. The alternative might be to use a thermal chamber with the application not running at full load. Getting an accurate temperature measurement will be a challenge with the soldering iron or heat gun method. Do you need a better value for the over temperature shutdown feature, presuming it has one?

Alan-san,

Thank you for your kind support and detailed description.
I got the following question from a customer.
(Because the enclosure temperature of the application is high,Customer is concerned)
"If Tj=125C is exceeded, How to operate this device?”

It is very possible that TPS5120 has no thermal protection at all. It is not mentioned in the datasheet or shown in the block diagram. While I do not know the specifics of TPS5120, I know for a fact that certain other controllers do not have any OTP feature as typically, the controller does not dissipate a lot of power as explained above.