I would like to know what the attenuation of the HMC542BLP4 is at power up (prior to SPI programming).
The serial controller used in HMC542BLP4 does not support Power Up mode, it will not power up to a defined state.
If your application requires the Dattn to be set to a defined attenuation state at power up, I would suggest our 6-bit Parallel/Serial Controlled digital attenuator, HMC624ALP4E. It has matching performances as the HMC542B and can support multiple Power Up modes and settings. Below is the link to our HMC624ALP4E datasheet.
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