This IC produces 29.6 kHz square wave and there is no external components. What it can be? I looked at all codes and I can’t find it.
It looks like a PIC10F200. The datasheet describes the marking code as having two characters of 'customer specific information', and two of 'alphanumeric traceability code', but in practice the first two digits appear to be the last two digits of the part number ('00' for PIC10F200) and last two are 'random'.
Here are some vendors' images of what purport to be a PIC10F200.
Based on the limited information you've given, it very likely a programmable timer IC. Possibly a LTC6906, based on the package and frequency you've listed (10kHz to 1MHz).
See if there is a resistor connected to one of the pins, and if you let us know the pin names I can find the exact part or at least a drop in. Specifically let me know pins tied to Vcc, Gnd, signal out, and the pin with a resistor on it. Also what the Vcc for the part is.