A Buck circuit using LTC3810 as conrtrol model, its output voltage decreases significantly as the output current increases, along with the decline of the system switch frequency.

1. the schematic of the application

Vin=84V, Vout=50V,fsw=1.04MHz,full load current is 2A.

control section: LTC3810

driver section:LMG1210

Switch transistor: high side:EPC 2012C   low side: EPC 2012C

2. The problem we were faced with in the experiment is that the output votage can not keep a stable value with the use of the loop feedback machanism provided by the LTC3810. To be specific, the output voltage tends to decrease dramatically compared to the expected vaule. At the same time, the switch frequency is in deline accordingly.

the test data

the gate signal of the high side switch mode and low side switch mode-to the get the information of the frequency

3. Now we have taken three possible reasons that may lead to the abnormal phonomona.

(1) the voltage source we used to supply the circuit to work( but it seems like that it is not the matter where it comes from)

(2) the revalent device of the compensation we have changed in order to meet the demand of the practical engineering .

3) the electroic load in the experiment shows no signal of destructions.

Therefore, currently, I have not yet figured out what mistakes results in the bad experiement results. I hope you could provide me some useful ideas or methods to solve the urgent problem.