I know VDD,VCC,VEE and VSS and what they stand for. But when I came across this circuit:
I saw this. Those PVDD and AVDD terms? What to do they convey or stand for?
This circuit is amplifier circuit of PAM8403 DS.
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3 Answers
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The answer is right in the datasheet for PAM8403:
So P stands for "power" and A stands for "analog".
Chip vendors and board designers are essentially free to name pins or nets however they like. The "AVDD" designation is pretty common for the pin powering the analog part of a chip. I've never seen "PVDD" before, but I don't work in audio, so I wouldn't know if it's common or not in that field.
answered Aug 30, 2018 at 4:49
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1\$\begingroup\$ @SpehroPefhany, ... I'm actually seeing it the other way around. \$\endgroup\$ Aug 30, 2018 at 4:51
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\$\begingroup\$ That was a close race. I guess I take the bronze medal... \$\endgroup\$– user105652Aug 30, 2018 at 4:53
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The first thing you should do when trying to figure this out is to find and thoroughly read the datasheet. You will find the answer on page 2:
PVDD (Power Vdd) is the pin that the current to drive the speakers comes from (a relatively high current). VDD/AVDD is analog Vdd which is the lower current that is used to power the rest of the chip. They are kept separate so they can be bypassed separately to keep PVDD from affecting AVDD.
answered Aug 30, 2018 at 4:49
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This datasheet explains it all, but basically Vdd is for the analog pre-amp portion of the IC, while PVdd is for the digital/PWM portion and audio outputs, so can draw much more current than the Vdd pin.
It is common sense to separate the 2 supplies even if they run at the same voltage. If not then even more reason to separate them. This way you can use external RCL filters for each power input so digital noise does not get back into the analog section.
For a class D amplifier that could cause severe distortion. Be sure to have 100 nF capacitors right at each power pin and connected to a broad ground plane. Follow manufacture guidelines for IC board layout pattern to get the best performance.