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UltraZed MGTRAVTT Current Requirement

kgervel

I'm doing a custom carrier card design for the UltraZed SOM, and it is stated several times in the UltraZed-EG SOM Designer's Guide that the MGTRAVTT voltage rail (1.8V) is required to supply 1A to the SOM (see p. 29, table 16). 

However, in the UltraZed Carrier Card design, MGTRAVTT is provided by the LDO output on the IRPS supply, which only has an output of 0.3A.  How does this work?

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    The MGTRAVTT rail is typically a low power draw, transciever power is highest on the AVCC rail. The UltraZed SOM was designed during early release of the silicon so we were much more conservative with our requirements (for power obviously designing with additional margin). In most designs the current draw on this rail will be relatively low. Always use XPE to generate power estimates when designing your own carrier specific to the interface you plan to design. These figures will be most accurate for your design. Hopefully that makes sense. You will often see supporting rails (non AVCC rails) powered by LDOs because of the lower current requirement and the high noise sensitivity requirements.

    Thanks

    Chris