ADAU1467 PLL Loop Filter capacitance spec

SigmaDSP & SigmaStudio takumi3952 Feb 25, 2019 00:00 3 replies Original on forum ↗

takumi3952 Question

Feb 25, 2019 00:00

Hi,

Please let me know about the capacitor used in the PLL Loop filter circuit of the ADAU1467 evaluation board as followings.

It is difficult to obtain the same model number as the capacitor used for C19 5.6nF .

We plan to replace it with another type model to create the original board.

Which is recommended in this case?

1. A capacitor with a same size of 1005 and a different capacity of 4.7nF.

2. A capacitor with a same size of 1005 and a different capacity of 6.8nF.

3. A capacitor with a different size and a same capacity of 5.6nF.

Thanks and Regards,

Audio Signal Processors

adau1467

SigmaDSP Audio Processors

SigmaDSP

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DaveThib Reply

Feb 26, 2019 00:00

Hello takumi3952,

Option 3. Keep the value the same but change the size. Also, we strongly recommend they use an C0G/NP0 type of capacitor. They are more stable over temperature.

Dave T

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takumi3952 Reply

Feb 27, 2019 00:00

Hi Dave,

Thanks for your reply.

According to information from the customer, 5.6nF capacitors are difficult to obtain for mass production.

I have to think about an alternative.

For example, is there any problem with parallel layout of capacitors of 4.7nF and 1.0nF?

In this case, the total capacity will be 5.7nF and the capacity will be changed.

Which is the most practical alternative?

Thanks and Regards,

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DaveThib Reply

Feb 28, 2019 00:00

Hello Takumi3952,

Here is what is in the datasheet:

Components that are valued within 10% of the recommended component values and with a 15% or lower tolerance are suitable for use in the loop filter circuit.

5.7nf is less than 2% from 5.6nf. So if they use 10% tolerance components then they will remain within the 15% of the original target value. So this should be fine.

Dave T

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