alc268 Realtek Semiconductor Corporation, alc268 Datasheet - Page 77

• Manufacturer Part Number: alc268
• Description: 2+2 Channel High Definition Audio Codec
• Manufacturer: Realtek Semiconductor Corporation

10.5. Digital Microphone Implementation
This section describes the ALC268 series digital microphone implementation. There is one Clock output
pin and 1 Data input pin in the ALC268 series. The ALC268 series provide the clock signal to the digital
microphone. When the digital microphone receives the external sound input, it converts the analog signals
to digital in a 1-bit format. The 1-bit data is delivered to the codec though the data input pin. The Digital
Filter in the audio codec converts the 1-bit data stream into Pulse Code Modulation (PCM) data. The
PCM data is sent to the HDA controller through the HDA link.
The ALC268Q supports a two-wire interface (DMIC-CLK and DMIC-DATA) for the digital microphone
and operates in single-channel (mono type) or stereo-channels (stereo) digital microphone mode. One pin
is clock output to the digital microphone, and the other two are serial pins. The default clock output is
2.048MHz.
The ALC268 and ALC268-VB1 support a 3-wire interface. DMIC-CLK is clock output to a digital
microphone, DMIC-12 and DMIC-34 are data inputs from a digital microphone. With the extra data pin
DMIC-34, the ALC268 and ALC268-VB1 can support up to 4 channels of digital microphone input.
In Type 1 (Figure 24), the ALC268 uses one data pin to support mono input from digital microphones
with an LMV1024 (L), SPD0205ND (L), or AKU2000 (L).
In Type 2 (Figure 24), the ALC268 uses one data pin to support stereo inputs from digital microphones
with an LMV1024/1026 (L/R), SPD0205ND (L & R), or AKU2000 (L & R).
2+2 Channel High Definition Audio Codec
Figure 23. Digital Microphone Implementation-1
Figure 24. Digital Microphone Implementation-2
69
Track ID: JATR-1076-21
ALC268 Series
Datasheet
Rev. 1.3