does low power sbr necessary for AAC HE support, or normal SBR is enough?

Can you rephrase your question and be a little more specific? What are you referring to by "low power SBR" ?

OK,

suppose i programmed a decoder capable of decoding in only one of the modes - SBR or low power SBR, will it be considered full aac HE.
(as i understood acc HE shoould support SBR and PS)

If you want to implement SBR decoder only, then you dont need to implement both of them. But if you are gonna support PS, then at least you should implement a HQ SBR, as PS does not work along with LP SBR.

thanks, thats really helpfull