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Part Number: PCM1865-Q1
our customer is considering designing in PCM1865-Q1 and using it in M/S mode.
We have a few questions:
I can share block diagram of what we want to accomplish if it would be helpful.
Thanks for your support.
Please refer to below comments:
-Diego Meléndez López Audio Applications Engineer
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In reply to Diego Melendez:
thank you, it helped us moving forward.
Based on your feedback, we're attaching two block diagrams (zip below) and would have the following questions:
Thank you,Kind regards,Customer
In reply to Bart:
Thanks for the feedback, please refer to the comments below.
Both setups are valid for the PCM186x devices, the only comment I have is that the I²C bus should be shared between the devices as it seems from the diagram that the control interface of PCM186x is daisy chained.
Both approaches are valid and should work properly, the decision to choose between one or the other is mainly driven by end-user preference or limitations of the system. Please keep in mind that each solution would require a specific serial interface configuration.
Buffers are not really required as long as the ICs are placed relatively close, which I think is the case.
If differential input is used, the setup should be the same in terms of digital audio interface. The only change would be on the input circuit architecture and device configuration.
We have a reference design, TIDA-01454, which uses two PCM1864 (similar to PCM1865, but with 130dB performance) and 8-mic. You can look at that schematic and use it as reference.
Unfortunately we are not currently supporting driver development for our devices, I know there are a couple drivers available on some repositories for Linux on the web, but right now we might not be able to help with any change or configuration of them.
many thanks for your feedback. It helps.
Regarding differential input, as datasheet suggests, the only difference is in the input filter. Is that what we refer to when we state that the only difference is in input circuit architecture and device configuration?
Is there any additional difference in input circuit besides that for using analog mems with differential outputs? Also, since reference designs doesn’t involve power supply circuitry (it is taken from one of the DSP boards), It would be useful to know what is the preferred way of powering this IC’s. Can they handle properly designed switcher or is a linear regulator a must?
Thank you,Best regards
Correct, the input circuit connection is the only difference between using a single-ended or a differential input configuration. It is possible that the circuit requirements for a given mic changes, but for the PCM186x point of view, the only difference is on the signals provided to the input pins.
A clean power supply is required to have the expected performance of the device, it is a system-level decision to select a proper power supply for the ADC. We usually recommend to use linear regulators, but I don;'t see a problem with using a switching supply as long as you make sure a clean voltage rails is provided to the device.
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