REG103-A thermal protection

Timothy Starr

Hello-

During recent high temperature testing, it was observed that the REG103GA-A with 3.3V in and 3.0V out, the output voltage jumped to 3.3V at 100 degrees C. The same thing happens to the part with 6V in and 5V out - the output jumps to the input voltage, potentially causing failues of the load components. Is this normal? What is the root cause? How can it be prevented? Is there another component which we can use which will not exhibit the problem? Thanks and Best Regards,

-Tim Starr on behalf of AM@NI

over 12 years ago

0 Jeffery Pfarr over 12 years ago

TI__Genius 14317 points

Tim,

Can you tell us what the load current is and provide a schematic? Do they use a "boost" resistor?

0 Ed Walker over 12 years ago in reply to Jeffery Pfarr

Prodigy 5 points

No it is not normal.
The part has thermal shutdown that will turn off the internal pass fet at 150C junction temperature.
With the fet OFF it will not source current to the output.

The linear regulator will not sink current, so if something else is pulling up the output it can not prevent that.

If the upper resistor in the feedback divider opens up then it will try to force Vout=Vin, trying to get 1.295V on its ADJUST pin.

0 Richard Elmquist over 12 years ago in reply to Ed Walker

TI__Mastermind 45250 points

Ed and Jeff,

I am going to move this to the internal forum and I will post the customer's comments and schematic. I will copy you on the new forum post.]

Thanks for your help with this!

Richard Elmquist

Power management

Power management forum

REG103-A thermal protection