FAQs

ADMP404 - FAQ

Is a microphone with -37 dBV sensitivity better than a microphone with -42 dBV (lower) sensitivity?

Not necessarily. The optimal sensitivity depends on the customer's application and design constraints. Most analog ECM and MEMS mics have -42 dBV sensitivity.

Is -26 dBFS digital mic sensitivity higher than -42 dBV analog mic sensitivity?

The dBFS and dBV units cannot be compared directly because they use different references. Please see AN-1112 for additional information on microphone specifications

Could direct soldering to a PCB cause vibration pickup by the mic?

MEMS microphones are much less sensitive to vibrations than ECMs due to much lower membrane mass.

Could software be used to eliminate competitor mics’ response peaks?

Small (few dB) peaks can be eliminated; large sharp peaks (20+ dB) are practically impossible to correct.

Due to open package, are there problems with humidity (condensation) when cooling down/heating up the device?

We have done extensive temperature/humidity cycling testing and found no problems with the microphones.

Can ADI MEMS mics be soldered to a flex PCB?

Yes. Handling considerations in the datasheet and AN-1068 should be followed during assembly.

Can digital microphone PDM output be interfaced with I²S directly?

A PDM output microphone, such as the ADMP421, cannot directly interface to an I2S port. This microphone should be connected to the PDM input on codecs such as the ADAU1361 and ADAU1761. The ADMP441 MEMS microphone has an I2S output that can be connected directly to a processor or codec's I2S port.

What is the recommended thickness of the PCB for the ADI MEMS mics?

Any PCB thickness can be used without affecting the microphone’s response.

Why not design a mic with the highest sensitivity?

High sensitivity is not always a benefit. For a near-field (close-talking) use the loud signal can overload a sensitive microphone, which creates high distortion.