Hi,
Our team is currently in the process of designing a DC/DC converter utilizing the UCC256402 and incorporating GaN devices.
Our objective is to achieve a higher working frequency, exceeding 500kHz.
However, we encountered difficulties in maintaining stable operation when the burst mode is disabled, as it leads to fluctuations in the switching frequency.
To address this issue, we implemented Option6. Despite depopulating the resistor between RVCC and LL/SS, we faced challenges in successfully exiting the burst mode.
There are the basic parameters that we used:
Vin: 380Vdc
Vout: 24V
Iout_max: 6A
Lm=56uH, Np:Ns:Nf=32:4:3
Lr=6.3uH
Cr=20nF
Cvcr_upper:50pF, Cvcr_lower:390pF.
Would you please help to check the reason, and give us some advice.
I can offer more information if you need.
B.R.
Victor
