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Part Number: PCM1861
hi i'm wondering if the pc1861 need input driving, i'm connecting a analog microphone...if it does need, what op amps should i use\
The PCM1861 is able to drive analog mic inputs directly as it features an integrated PGA in the front-end. There is no need to use an external microphone driver stage as the PGA in the device should be able to increase the mic signal level to the desired line level.
-Diego Meléndez López Audio Applications Engineer
In reply to Diego Melendez:
In reply to Timotei Fogorosiu:
It seems the schematic you are mentioning was not uploaded, so I cannot see it. If an OpAmp is used before the inputs of the PCM1861, probably the signal was conditioned to make it compliant with the device input specs. AS I cannot see the schematic, I am not sure about the function of caps you mention, but based on the values they should be decoupling caps.
7870.schemat2.pdfhi sorry i forgot to attach the schematic...
Thanks for sharing the schematic. I think for that particular application the OpAmp is used to condition the input signal, which is not required as long as your input signal is compliant with the device specs. For microphone usage, no pre-amplifier is needed as the PCM1861 has an internal PGA in the front-end.
Regarding the ferrite and caps from your question, effectively those are decoupling caps but the circuit connection is incorrect, the caps should be directly tied to the device pin. The ferrite can be connected after the caps to the power supply to filter noise from the main supply.
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