ICS-40180
APPLICATIONS INFORMATION
CODEC CONNECTION
The ICS-40180 output can be connected to a dedicated codec microphone input (see Figure 9) or to a high input impedance gain
stage. A 0.1 µF ceramic capacitor placed close to the ICS-40180 supply pin is used for testing and is recommended to adequately
decouple the microphone from noise on the power supply. A DC blocking capacitor is required at the output of the microphone. This
capacitor creates a high-pass filter with a corner frequency at
fC = 1/(2π × C × R)
where R is the input impedance of the codec.
A minimum value of 2.2 μF is recommended in Figure 9 because the input impedance of some codecs can be as low as 2 kΩ at their
highest PGA gain setting, which results in a high-pass filter corner frequency at 37 Hz. Figure 10 shows the ICS-40180 connected to
an op amp configured as a noninverting preamplifier.
MICBIAS
0.1 µF
ADC
OR
CODEC
VDD
2.2 µF
MINIMUM
ICS-40180
INPUT
OUTPUT
GND
Figure 9. ICS-40180 Connected to a Codec
1.8-3.3 V
GAIN = (R1 + R2)/R1
R1 R2
V
REF
0.1µF
VDD
V
AMP
OUT
1µF
MINIMUM
ICS-40180
OUTPUT
GND
10kΩ
V
REF
Figure 10. ICS-40180 Connected to an Op Amp
Page 8 of 14
Document Number: DS-000021
Revision: 1.2
TDK [ TDK ELECTRONICS ]
