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LDOs & power supplies for AVDD, CVDD, IOVDD on VS1003

Posted: Wed 2019-05-01 2:43
by Berry
Hello

I’d like some clarification regarding the power supplies required for the VS1003 chip. According to the datasheet, the following power supplies are required:

• AVDD (2.6V – 2.85V)
• CVDD (2.4V – 2.85V)
• IOVDD ((VDD-0.6) – 3.6V)

And it’s implied that separate power supplies/LDOs are required for each. However, according to http://www.vlsi.fi/fileadmin/app_notes/ ... 11to03.pdf, it says that in 2011, the chip was requalified to allow operation on a single voltage for all 3 in the 2.6V to 2.85V range.

I have the following questions:

• Does that imply that one can use a single shared LDO for all 3 instead of 3 separate LDOs?

• If one LDO (say 2.85V output) is used as power supply for all 3, do you expect performance/noise impact? Other components on the same board (MCU, speaker, etc..) will consume ~500mA. I assume this is not a good idea, but I'd like to confirm in light of the note quoted above in the PDF.

• How about using 1 LDO for both AVDD and CVDD (2.85V) and separate LDO for IOVDD (3.3V), is that good for performance, or still better to use 3 separate LDOs?

Thanks,
Berry

Re: LDOs & power supplies for AVDD, CVDD, IOVDD on VS1003

Posted: Fri 2019-05-03 4:40
by Berry
Any update or feedback? Thanks!

Re: LDOs & power supplies for AVDD, CVDD, IOVDD on VS1003

Posted: Fri 2019-05-03 11:34
by Hannu
Yes. You can use single voltage for all power inputs of VS1003.

Designing the power distribution on board might become interesting. Simple power and GND layer with capacitor always when going in or coming out from power layer might be good start.

However with separate regulators you get better PSNRR and easier routing on layout and as a bonus you get nicer mental model of return currents.

It is possible to make low noise power supply for VS1003 in either way but it requires good layout. If in doubt, use separate regulators.

Re: LDOs & power supplies for AVDD, CVDD, IOVDD on VS1003

Posted: Tue 2019-05-07 20:26
by Berry
Thanks Hannu. I have another unrelated question so will post shortly in another thread.

Regards,
Berry