CS48L32 datasheet(27/192 Pages) CIRRUS

27 / 192 page

DS1219F4

Cirrus Logic

CS48L32

4.2 Input Signal Path

The voltage reference for the PDM interfaces is selectable, using INn_PDM_SUP; each interface may be referenced to

VOUT_MIC or MICBIAS1. For DMIC use cases, the voltage reference for each input path should be set equal to the power

supply of the respective microphones.

A pair of digital microphones is connected as shown in Fig. 4-10. The microphones must be configured to ensure that the

left mic transmits a data bit when INn_PDMCLK is high and the right mic transmits a data bit when INn_PDMCLK is low.

The CS48L32 samples the DMIC data at the end of each INn_PDMCLK phase. Each microphone must tristate its data

output while the other microphone is transmitting.

Note that the CS48L32 provides integrated pull-down resistors on the INn_PDMDATA pins. This provides a flexible

capability for interfacing with other devices.

Figure 4-10. DMIC Input

Two PDM channels are interleaved on INn_PDMDATA, as shown in Fig. 4-11. If two microphones are connected to

provide a stereo interface, each microphone must tristate its data output while the other microphone is transmitting.

Figure 4-11. PDM (DMIC) Interface Timing

Digital Mic

VOUT_MIC or MICBIAS1x

GND_A

Digital Mic

VDDCLK DATA

CHAN

VDD

INn_PDMDATA

INn_PDMCLK

PDM (Digital

Microphone )

Interface

The PDM inputs are referenced to

VOUT_MIC or MICBIAS1.

The supply for each digital microphone

should provide the same voltage as the

applicable reference.

GND

INn_PDMCLK clock

INn_PDMDATA pin

(Left and right channels interleaved)

Left mic output

Right mic output

Hi-Z

CS48L32 Datasheet(PDF) 27 Page - Cirrus Logic