Buck Converter Module issues

[FotatoPotato]

Hi all,

So I just finished building a breadboard DC-DC converter module (on a pcb)  based off of the LTC3864. I have my converter set up to operate in burst mode since every time I set it to run in Pule skipping mode it pulls 100mA and the LTC3864 reaches 100C within seconds. My design is based on the DC2434A evaluation board with only minor changes made to the feedback line (I'm just using a 10K resistor and 100K pot to set the output voltage.

Anyway, when there is no load attached the converter board works fine and the output can be adjusted from 0.8v all the way to 30v with an input of 32v. This is great and all but the problems occur once I attach a load on the output.  I set the output of the converter to 12v and hooked it up to my electronic load. I then started to increase the current draw in steps of 10mA. I also added a thermocouple on the LTC3864 to monitor its temp. I designed the converter to go up to 5A but once I draw over 60mA the LTC3864 quickly heats up to 80C and then shuts down and pulls a constant 140mA with 0v on the converter output. I have gone over my schematic and the eval board schematic multiple times and I can't figure out what's going on. Do any of you guys know what's going on?

Thanks 

[paulca]

I tried to breadboard a DC-DC converter and it didn't work either.

I soldered it onto proto-board and it worked fine.  They are usually sensitive to the resistance, flakey connections and capacitance in the breadboard.

You shouldn't really attempt to run anything near 5A through a breadboard, 1A is really the limit.

Try implementing the "Typical application" circuit in the datasheet on a bit of proto board and see if it works.