• ADMP421 tristated output


    I’m hoping you can help me work through an issue I’ve run into with the ADMP421 digital microphone. I understand the format of the pulses now, but the output doesn’t behave exactly like what’s shown in the data sheet.

    The microphone has an input…

  • ADMP421 PDM characteristics questions


    My customer is using the ADMP421 digital microphone and are working to improve the way we monitor the output of the microphone. They cannot find a document that describes the format of the PDM output from the ADMP421 anywhere on the ADI web site…

  • ADMP421 bias in output signal.

    I am working with the ADMP421 MEMS microphone and the ADAU1761. I am also using the ADAU1761 as a codec for an extenal microphone. When the system is configured for the external microphone, there is a zero bias on the output and the high frequency content…

  • ADMP421 - how to check...

    Hello All,

    I have a board where ADMP421 is used. We did a rework (using hot air) and noticed the following behaviour:

    +3V3 - is present and correct

    GND as well.

    L/R - is low

    CLK input is 2.048MHz

    Data out is present. (See captured image below)

  • Configuring ADAU1761 to work with ADMP421?

    In SigmaStudio, there is a Hardware Configuration option to enable Digital Mic. After that is enabled, does the mic signal from the ADMP421 eval card simply come in to a regular input block on channel 0? CN-0078 doesn't say anything about configuring…

  • Low pass filter for ADMP421 MEMS digital microphone

    Wish to use a decimating filter in a microcontroller to interface a MEMS microphone (ADMP421). Has anyone used a microcontroller to do this?The sampling frequency is 1MHz (the minimum requirement for the MEMS mic).

    We eventually want to recover a base…

  • Can you capture audio with EVAL-ADAU1761Z?

    I'd like to capture the audio with my digital ADMP421 microphones on my EVAL-ADAU1761Z board. Is this possible? If not, does Analog make an eval board that works the ADMP421 microphones?



  • RE: ADAU1761 DC gain in the digital mic path

    Hi Tyler,

    Thanks for the response.

    Adding to the above, ADAU1761 has two omnidirectional MEMS microphones, which are analog devices part number ADMP421 ICs (U3 and U4 on the board). About this microphones, how many data bits the ADMP421 is giving and…

  • Can a microphone's PDM output be directly interfaced to an I2S port?

    Some MEMS microphones like the ADMP421 have a PDM data output. Can this be conected directly to an I2S input on a codec or DSP?