LM1084: LM1084

Hi Tom, 

Will you help to provide more details on the oscillation problem you have experienced? 

Regards, 

Jason

This is related to an earlier problem that I had, if you go to the top of the page, and click on the origonal question it will take you to a description of the issue, and the responce that I recieved.

The original post is related to the thermal shutdown. Will you please help to confirm your Vin, Vout and Load current when the oscillation starts? 

Thank you,

Jason

Votage into the requlator is 13.8v. The voltage level shown in the o'scope pics is the voltage out, 13.1v before load applied, the drop in voltage on the scope is when the load is applied. As doculmented on the pics, the oscillating occures somewhere between 6.1 and 6.2 amps. Load is an electronic load set to current control. Oscilation does not occur if I use chill spray on the regulator.

With 4.27watts of power, if KTT package is used, the junction temperature rise is estimated to be 172C; with NDE, the temperature rise is 97C. The actual junction temperature will be on top of the ambient temperature. It's not oscillation, the on and off of the output is related to the thermal shutdown. 

Yes, we resolved that this is the problem on my last question, the question now is has there been any changes to this component that might account for it reacting differently when used in the same way in 2013? I am being told by my end user that it did not react this way in 2013.

Hi Tom,

To my knowledge there haven't been changes to the part since then. Another factor that will affect the thermals besides Vin, Vout, and Iout is board layout. Are they also using the same board layout or is it a new design? 

Best regards,

Nick