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.

LM5069: LM5069 doesn't turn off a MOSFET under short circuit

Genius 9880 points
Part Number: LM5069

Hi Team,

Good day, I received query from customer regarding this device. For me to not miss any information, Ill copy query below.

"

. I have a problem with testing LM5069. It was decided to use this IC in couple with a MOSFET as a electronic fuse, which turns off the cirquit at overvoltage and overcurrent. I used TI's calculator to determine cirquit parameters. Rated voltage is 24V, maximum allowable voltage is 30V, maximum allowable current is 12A.

Now I trying to test a prototype. Unfortunately, I have no power supply unit rated at 12A. To quick test the IC, I decided to change a value of current limiting resistor. Instead of 0.004 Ohm I'am using 0.04 Ohm resistor.

When output is shorted, the voltage on source is falls down but MOSFET is still opened a little bit. So there is no a proper switching off.
I am attaching figures with an original shchematic (Both 0.002 Ohm resistors are replaced by 0.02 Ohm ones) and oscillogramm with gate voltage, source voltage and timer pin voltage

7851.LM5069.zip

"

Thank you and looking forward for your kind response.

Regards,

Maynard