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Electronics => Projects, Designs, and Technical Stuff => Topic started by: sidlauskas on January 27, 2019, 01:46:56 pm

Title: PCM5102A in 1.8V mode. Separate 0.1 and 10uF caps for DVDD and LDOO?
Post by: sidlauskas on January 27, 2019, 01:46:56 pm
Hi,

I found in the datasheet (33 page, 11.5.1) that when using PCM5102A in 1.8V mode, DVDD and LDOO should be both connected to external 1.8V. What's not clear to me is if I still have to put separate 0.1 and 10uF caps for both DVDD and LDOO pins as shown in the schematic provided in their datasheet. Here's how it looks like in my schematic:

(https://i.imgur.com/12lLynE.jpg)

Is this correct? Thanks
Title: Re: PCM5102A in 1.8V mode. Separate 0.1 and 10uF caps for DVDD and LDOO?
Post by: dmendesf on January 27, 2019, 02:06:49 pm
Pins are so near that this won't make a difference. You can put one of each without fear.
Title: Re: PCM5102A in 1.8V mode. Separate 0.1 and 10uF caps for DVDD and LDOO?
Post by: mvs on January 27, 2019, 05:06:29 pm
Quote from: sidlauskas on January 27, 2019, 01:46:56 pm
I found in the datasheet (33 page, 11.5.1) that when using PCM5102A in 1.8V mode, DVDD and LDOO should be both connected to external 1.8V. What's not clear to me is if I still have to put separate 0.1 and 10uF caps for both DVDD and LDOO pins as shown in the schematic provided in their datasheet.
I see no practial reason to cheap out on decoupling caps... It costs almost nothing and would not add any new item to your BOM.
Put at least separate 100nF to LDOO, so if you decide later to use 3V IO levels, you can still cut the trace between LDOO and DVDD.
Title: Re: PCM5102A in 1.8V mode. Separate 0.1 and 10uF caps for DVDD and LDOO?
Post by: sidlauskas on January 27, 2019, 06:19:14 pm
Quote from: mvs on January 27, 2019, 05:06:29 pm
Quote from: sidlauskas on January 27, 2019, 01:46:56 pm
I found in the datasheet (33 page, 11.5.1) that when using PCM5102A in 1.8V mode, DVDD and LDOO should be both connected to external 1.8V. What's not clear to me is if I still have to put separate 0.1 and 10uF caps for both DVDD and LDOO pins as shown in the schematic provided in their datasheet.
I see no practial reason to cheap out on decoupling caps... It costs almost nothing and would not add any new item to your BOM.
Put at least separate 100nF to LDOO, so if you decide later to use 3V IO levels, you can still cut the trace between LDOO and DVDD.

In 3.3v mode LDOO must be connected to GND, so it wouldn't be enough to cut that trace
Title: Re: PCM5102A in 1.8V mode. Separate 0.1 and 10uF caps for DVDD and LDOO?
Post by: mvs on January 27, 2019, 09:50:11 pm
Quote from: sidlauskas on January 27, 2019, 06:19:14 pm
In 3.3v mode LDOO must be connected to GND, so it wouldn't be enough to cut that trace
LDOO is output of internal 1.8V LDO voltage regulator and positive supply rail for internal logic... why on earth it needs to be grounded?
Title: Re: PCM5102A in 1.8V mode. Separate 0.1 and 10uF caps for DVDD and LDOO?
Post by: sidlauskas on January 27, 2019, 10:06:04 pm
Quote from: mvs on January 27, 2019, 09:50:11 pm
Quote from: sidlauskas on January 27, 2019, 06:19:14 pm
In 3.3v mode LDOO must be connected to GND, so it wouldn't be enough to cut that trace
LDOO is output of internal 1.8V LDO voltage regulator and positive supply rail for internal logic... why on earth it needs to be grounded?

It seems you're correct. Sorry for confusing and thanks for your input!