Datasheet

Microphone Amplifier with AGC and
Low-Noise Microphone Bias
MICBIAS NOISE vs. FREQUENCY
MAX9814 toc10
FREQUENCY (Hz)
MICBIAS NOISE (nV
RMS
/√Hz)
10k1k100
100
1000
10,000
10
10 100k
SMALL-SIGNAL PULSE RESPONSE
MAX9814 toc11
200μs/div
V
MICIN
10mV/div
0V
V
MICOUT
500mV/div
0V
C
L
= 10pF
TURN-ON RESPONSE
MAX9814 toc12
20ms/div
V
SHDN
5V/div
0V
V
MICBIAS
2V/div
0V
V
MICOUT
1V/div
0V
V
OUT
vs. V
IN
MAX9814 toc13
V
IN
(mV
RMS
)
V
OUT
(V
RMS
)
10050
0.25
0.50
0.75
1.00
0
0 150
V
TH
= 1V
V
TH
= 0.75V
V
TH
= 0.5V
AGC ENABLED
GAIN = 1
V
OUT
vs. V
IN
MAX9814 toc14
V
IN
(mV
RMS
)
V
OUT
(V
RMS
)
302010
0.25
0.50
0.75
1.00
0
040
V
TH
= 1V
V
TH
= 0.75V
V
TH
= 0.5V
AGC ENABLED
GAIN = 0
V
OUT
vs. V
IN
MAX9814 toc15
V
IN
(mV
RMS
)
V
OUT
(V
RMS
)
105
0.25
0.50
0.75
1.00
0
015
V
TH
= 1V
V
TH
= 0.75V
V
TH
= 0.5V
AGC ENABLED
GAIN = UNCONNECTED
ATTACK TIME
MAX9814 toc16
200μs/div
V
MICOUT
500mV/div
C
CT
= 47nF
0V
ATTACK TIME
MAX9814 toc17
200μs/div
V
MICOUT
500mV/div
C
CT
= 100nF
0V
HOLD AND RELEASE TIME
MAX9814 toc18
20ms/div
V
MICOUT
500mV/div
C
CT
= 47nF
A/R = GND
0V
Typical Operating Characteristics (continued)
(V
DD
= 5V, C
CT
= 470nF, C
CG
= 2.2µF, V
TH
= V
MICBIAS
x 0.4, GAIN = V
DD
(40dB), AGC disabled, no load, R
L
= 10kΩ, C
OUT
= 1µF,
T
A
= +25°C, unless otherwise noted.)
MAX9814
Maxim Integrated
5