INMP421

CONNECTING PDM MICROPHONES

A PDM output microphone is typically connected to a codec with a dedicated PDM input. This codec separately decodes the left and right

channels and filters the high sample rate modulated data back to the audio frequency band. The codec also generates the clock for

the PDM microphones or is synchronous with the source that generates the clock.

Figure 10 and Figure 11 show mono and stereo connections between the INMP421 and a codec. The mono connection shows an

INMP421 set to output data on the right channel. To output data on the left channel, tie the L/R SELECT pin to VDD instead of GND.

Figure 10. Mono PDM Microphone (Right Channel) Connection to Codec

CLOCK OUTPUT

CODEC

0.1µF

1.8V TO 3.3V

GND

L/R SELECT DATA

VDD

DATA INPUT

Page 12 of 21

Document Number: DS-INMP421-00

Revision: 1.0.