Hello Mr. Taichi,
I've posed your questions to people who are more familiar with the LM98620 and I'm still waiting for their response. That's why I have not got back to you earlier. I will keep you posted as soon as I get your answers.
In the meantime, I think it'd be better if you also contact me through my own email account for more details and discussions:
hooman.hashemi@ti.com
Regards,
Hooman
