We checked following thread.
Is there a release date for the HMC521A?
Our customer is waiting for the HMC521ALC4 release.
They were considering replacement from HMC521 to HMC521A, and bought the last buy, but the stock was gone.
The schedule to be released is still remain in Summer 2018 ?
The schedule for the HMC521A has not still not changed. We are still targeting release for this summer. Around June-July.