Using buck-boost converter as flyback converter? (XL6008 vs LM2588)

[LinuxHata]

Hello.

As old school IC's like LM2588, LT1370 and others are getting rare, expensive and less efficient, thinking about replacing them with something more modern, cheap, but still in beginner-friendly physical packaging.

My task is to get from 5VDC input, 200VDC output at 20mA (4 watts).
I have built such circuit with LT1370 or LM2588 and some Coilcraft transformers and they work just fine. But both components are quite expensive, so I'm thinking about going into cheap side. What about replacing LM2588 with XL6008 ? they both appear to have similar circuits in datasheet, so should work without any issues, but what are these CDC capacitors for XL6008? they needed for SEPIC operation? what if I remove them, since my Vout is always larger than Vin ?

[m k]

Is your always a really always or just mostly always.