AK7755EN_16 Datasheet, PDF (99/109 Pages) Asahi Kasei Microsystems – DSP with Mono ADC Stereo CODEC + Mic/Lineout Amp

[AK7755]
■ Digital Microphone Interface
1. Digital MIC Connection
Four digital microphones can be connected to the AK7755 at the maximum. When DMIC1 (CONT1E:
D7) or DMIC2 (CONT1E: D4) bit is set to “1”, the #34 pin becomes DMDAT1 (digital microphone data
input), the #33 pin becomes DMCLK1 (digital microphone clock supply) pins, the #32 pin becomes
DMDAT2 pin and the #31 pin becomes DMCLK2 pin.
The DMCLK1/2 clock is an input to a digital microphone from the AK7755. The digital microphone
outputs 1bit data, which is generated by Modulator using DMCLK1/2 clock, to the DMDAT1/2 pin.
DMIC1/2 bit controls power up/down of the digital block (Decimation Filter and Digital Filter).
DCLKE1/2 bit (CONT1E: D5/D2) controls ON/OFF of the output clock from the DMCLK1/2 pin. When
the AK7755 is powered down (PDN pin= “L”), the DMCLK1/2 and DMDAT1/2 pins become floating
state. Pull-down resistors must be connected to DMCLK and DMDAT pins externally to avoid this
floating state. Figure 76 shows a stereo 4ch connection example.
AVDD
VDD
AMP



Modulator
Lch
VDD
AMP



Modulator
AK7755
DMCLK1(64fs)
100k
DMIC1 or DMIC2 bit = “1”
DMDAT1
100k
Decimation
Filter
DMIC1 bit = “1”
Digital
Filter
SDOUTAD
Rch
VDD
AMP



Modulator
Lch
VDD
AMP



Modulator
DMCLK2(64fs)
100k
DMIC1 or DMIC2 bit = “1”
DMDAT2
100k
Decimation
Filter
DMIC2 bit = “1”
Digital
Filter
SDOUTAD2
Rch
Figure 76. Connection Example for 4ch Stereo Digital Microphone
014006643-E-00
- 99 -
2014/10