Hi Sir,
I got a customer mentioned about PGA2505 application, there got one question need your support.
For the datasheet of PGA2505, there didn't mentioned about the application with single-end Amic. Could we pull-down the Vin- to GNDph directly? Or there have any other recommend circuit for the single-end Amic?
BTW, if we don't need the Phantom power, could we reduce/narrow down the circuit of differential design which is in datasheet page13?
Thanks,
George
HI George,
It is possible to connect a single-ended microphone, you could AC couple the input of the PGA2505, connecting Vin- to GND as below. If the VCC supply of the electret microphone exceeds the VA=+5V supply of the PGA2505, you may need add input voltage protection diodes as suggested on Figure 7 on page 12 of the datasheet. In general, the best performance with the PGA2505 is obtained using a differential output microphones.
Best Regards,
Luis
Hi Luis,
Thanks for the sharing, good to know that.
One more question, is the cap & resistor are both needed when Vin- connect to GND?
Please help to re-confirm it that I replace the protection diodes properly.
Thanks,
George
Hi Luis,
Sorry I got two more question:
1. Is the Red cycle means customer need to add a MOSFET after their Mic? If so, any recommend parts to them?
2. What is the suggestion value of R1?
Please help to reconfirm it, if customer's block diagram is correct?
Thanks,
George
George,
See circuit below with suggested input protection. The microphone needs to be AC coupled to the PGA2505 inputs using the series capacitors, the series resistors are typically kept small to reduce their noise contribution (typically 10-Ohm to 50-Ohm). The series capacitors at the inputs are Aluminum electrolytic capacitors to keep distortion low. The series resistor with the Mic supply will depend on the microphone supply requirements.
Thank you and Best Regards,
Luis
