max9860 Maxim Integrated Products, Inc., max9860 Datasheet - Page 28

• Manufacturer Part Number: max9860
• Description: 16-bit Mono Audio Voice Codec
• Manufacturer: Maxim Integrated Products, Inc.

16-Bit Mono Audio Voice Codec
The MAX9860 provides two differential microphone
inputs and a low-noise 1.55V microphone bias for power-
ing the microphones. In typical applications, the left
microphone is used to record a voice signal and the
right microphone is used to record a background noise
signal. In applications that require only one microphone,
use the left microphone input and disable the right ADC.
The microphone signals are amplified by two stages of
Figure 5. Microphone Input Block Diagram
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Microphone Inputs
MICBIAS
MICGND
MICLP
MICLN
MICRP
MICRN
1.55V
REG
gain and then routed to the ADCs. The first stage offers
selectable 0dB, 20dB, or 30dB settings. The second
stage is a programmable gain amplifier (PGA) adjustable
from 0dB to 20dB in 1dB steps. Zero-crossing detection
is included on the PGA to minimize zipper noise while
making gain changes. See Figure 5 for a detailed dia-
gram of the microphone input structure.
0/20/30dB
0/20/30dB
MAX9860
PREAMP
PREAMP
-
V
V
CM
CM
0dB to +20dB
PGA
PGA
AGC
0dB to +20dB
ADC
ADC
R
L