Hi Ben-san,
Change the part constants of the evaluation board to the following and output from 12 V output to 5 V output
Evaluation was carried out but it does not work properly. (U1 uses UCC 256302.)
<Constant change>
R23 = 6.04 kΩ → 858 Ω, R 25 = 147 k Ω → 51 k Ω.
The self-made transformer turn ratio for 5V output is as follows.
Np = 32 T, Ns = 1 T, Nc = 3 T
Lm = 820 μH
Lr = 20 μH (leakage L) + 40 μH (external L)
≈ 60 μH
In case
Through the above change, it operates with burst control, but the operating frequency is about 150 KHz and continuous control does not occur.
When the load is heavy, power can not be obtained and the output voltage drops.
What setting is bad?
