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TPV7002 DVDD/PLL/AVDD POWER RAIL QUESTION

WhiteHorse
Genius 4430 points

Hi

I have a customer considering the TPV7002.  Page 6 of the data sheet indicates 1.9V typ (1.8 min) for DVDD/PLL/AVDD (datasheet link below).

 http://www.ti.com/lit/ds/symlink/tvp7002.pdf

On page 42 of the TVP7002EVM User Guide  they are using a TPS70202 (U3), with "VOUT2" adjusted up to 1.9V for DVDD & AVDD.  However a fixed 1.8V regulator (U5, same page) is used for the VDD_PLL

http://www.ti.com/lit/ug/sleu098/sleu098.pdf

 looking at another design by Leopard Imaging Inc. they do just the opposite, running the PLL at 1.9V and the DVDD & AVDD at 1.8V.

Would it not be best to run all of them (DVDD/PLL/AVDD) at 1.9V to allow for some margin.  Is there a reason TI chose to power VDD_PLL at 1.8V (min) rather than 1.9V typical?

Regards,

John

  • 0
    TI__Genius 14317 points

    John,

    I would run all supplies at 1.9 V. The Data Sheet should always "trump" what you might see on an EVM or reference design. I think that the important thing is that the PLL supply should be a seperate, clean low noise supply. On the EVM, the DVDD and AVDD supplies come from the same source but are individually LC filtered. All supplies share a common GND plane as well.