What are the differences between these two parts?
The HMC641 (offered in die form and in LP4 and LC4 packages) will be obsolete in next month due to foundry/process discontinuation. The HMC641A was designed in a similar process from different foundry bytargeting form, fit, functional drop-in replacement of the HMC641. The HMC641A is recommended for new designs ad also can replace the HMC641 without any change in existing designs.
The HMC641A in LP4 and LC4 packages was already released to the production. The HMC641A is scheduled to be available by the end of this year.
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