PCM2906C: Using same 3.3V source for 2 codecs

Adam Bierman

Part Number: PCM2906C

I have a design that requires 2 x PCM2906C for 4 inputs and 8 output channels. I'm looking to use an external source for VCCI on my PCM2906C design to put it in high performance mode. I have a AP7361C-FGE-7 regulator set to output 4.02V across an RB520S-30-TP diode to give me 3.67V going into the codec. I'd like to split my 4.02V source with a second diode and run that second 3.67V source to a second coded. The regulator can supply up to 1A. Is there any reason a set up like this could not work?

Here is the codec portion of my schematic. The USB is coming in from an onboard hub, so I am powering the codec directly off my 5V source which feeds the 3.3V regulator. The audio portions of the circuit are on other pages.

over 4 years ago

0 Tom Hendrick over 4 years ago

TI__Guru**** 181041 points

Hi Adam,

I don't see any reason why you could not use the same power source for two PCM2906C devices.

0 Adam Bierman over 4 years ago in reply to Tom Hendrick

Intellectual 710 points

Great! Thank you, that seemed to be the case. I also wanted to ask about the VBUS power since I am using an onboard hub to the USB connection. If I remove the pullup on the D+ line (which would be read by my hub as a strap option if tied high which would disable the port), will I run into timing and power on issues if I use the 5V source on my board to provide main VBUS power? Should I shunt my main VBUS through a port switch so that it won't turn on until the hub is active?

0 Tom Hendrick over 4 years ago in reply to Adam Bierman

TI__Guru**** 181041 points

Hi Adam,

Good point - I would opt for for the port switch.

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PCM2906C: Using same 3.3V source for 2 codecs