19-2840; Rev 0; 4/03
Tiny, Low-Cost, Single/Dual-Input, Fixed-Gain
Microphone Amplifiers with Integrated Bias
General Description
The MAX9812/MAX9813 are single/dual-input, 20dB
fixed-gain microphone amplifiers. They offer tiny pack-
aging and a low-noise, integrated microphone bias,
making them ideal for portable audio applications such
as notebook computers, cell phones, and PDAs. These
amplifiers feature a 500kHz bandwidth, Rail-to-Rail®
outputs, an industry-leading 100dB power-supply rejec-
tion ratio, and a very low 0.015% THD+N. Power-saving
features include very low 230µA supply current and a
total shutdown mode that cuts the combined supply
and BIAS currents to only 100nA.
The MAX9812 is a single amplifier in a 6-pin SC70
package (2mm x 2.1mm) and the MAX9813 is a dual-
input amplifier available in an 8-pin SOT23 (3mm x
3mm) package. The MAX9813 has two inputs allowing
two microphones to be multiplexed to a single output.
The MAX9812/MAX9813 are offered in two grades. The
MAX9812L/MAX9813L are optimized for 3.3V supply
operation (2.7V to 3.6V). The MAX9812H/MAX9813H are
PC2001 compliant and are optimized for 5V operation
(4.5V to 5.5V). Both devices are specified over the -40°C
to +85°C extended operating temperature range.
o
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o
o
o
o
o
o
o
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o
Features
PC2001 Compliant
100dB at 217Hz Power-Supply Rejection Ratio
Very Low 230µA Quiescent Current
Low 0.015% THD+N
Available in Two Versions
MAX9812L/MAX9813L—2.7V to 3.6V
MAX9812H/MAX9813H—4.5V to 5.5V
Internal Low-Noise Microphone Bias Supply
2.3V for MAX9812L/MAX9813L
4.0V for MAX9812H/MAX9813H
100nA Low-Power Shutdown Mode
Rail-to-Rail Outputs
20dB Fixed Gain
Available in Tiny 6-Pin SC70 (2mm x 2.1mm) and
8-Pin SOT23 (3mm x 3mm) Packages
Extended Temperature Range -40°C to +85°C
MAX9812/MAX9813
Ordering Information
PART
MAX9812LEXT-T
MAX9812HEXT-T
MAX9813LEKA-T
MAX9813HEKA-T
PIN-
TEMP RANGE PACKAGE
-40°C to +85°C 6 SC70-6
-40°C to +85°C 6 SC70-6
-40°C to +85°C 8 SOT23-8
-40°C to +85°C 8 SOT23-8
V
CC
(V)
2.7 to 3.6
4.5 to 5.5
2.7 to 3.6
4.5 to 5.5
Applications
Notebook Computers
PDAs
Smart Phones
Car Kit Adapters
Digital Cameras
Video Tape Recorders
Pin Configurations, Selector Guide, and Typical Operating
Circuits appear at end of data sheet.
Rail-to-Rail is a trademark of Nippon Motorola Ltd.
Simplified Block Diagrams
V
CC
V
CC
SHDN
BIAS
REFERENCE
2.3V (L VERSION)
4.0V (H VERSION)
BIAS
REFERENCE
2.3V (L VERSION)
4.0V (H VERSION)
SHDN
IN1
IN
20dB
OUT
IN2
20dB
OUT
IN1/IN2
MAX9812
GND
GND
MAX9813
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Tiny, Low-Cost, Single/Dual-Input, Fixed-Gain
Microphone Amplifiers with Integrated Bias
MAX9812/MAX9813
ABSOLUTE MAXIMUM RATINGS
(All voltages referenced to GND)
V
CC
........................................................................-0.3V to +6.0V
All Other Pins..............................................-0.3V to (V
CC
+ 0.3V)
Continuous Current (IN,
SHDN,
IN1, IN2, IN1/IN2)...........±20mA
OUT, BIAS Short-Circuit Duration (to GND or V
CC
) ...Continuous
Continuous Power Dissipation (T
A
= +70°C)
6-Pin SC70 (derate 3.1mW/°C above +70°C) ..............245mW
8-Pin SOT23 (derate 8.9mw/°C above +70°C) ............714mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Junction Temperature ......................................................+150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
CC
= 3.3V, I
BIAS
= 500µA (MAX9812L/MAX9813L), V
CC
= 5V, I
BIAS
= 800µA (MAX9812H/MAX9813H), GND = 0V, R
L
= open,
SHDN
= V
CC
, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
GENERAL
Supply Voltage Range
Supply Current
Shutdown Supply Current
Amplifier Output Bias Voltage
Input Resistance
Voltage Gain
V
CC
I
CC
I
CC_SHDN
V
OUT_DC
R
IN
A
V
DC
Power-Supply Rejection Ratio
PSRR
OUT
Input referred, T
A
= +25°C
f = 217Hz
f = 1kHz
f = 10kHz
R
L
= 10kΩ to V
CC
/2
V
OH
Output Voltage Swing
V
OL
Output Short-Circuit Current
Small-Signal -3dB Bandwidth
Output Capacitive-Load Stability
Output Impedance
Output Slew Rate
I
OUT_SC
BW
C
L
Z
OUT
SR
R
L
= 1kΩ to V
CC
/2
R
L
= 10kΩ to V
CC
/2
R
L
= 1kΩ to V
CC
/2
Sinking or sourcing
V
OUT
= 10mV
P-P
No sustained oscillations
f = 1kHz
V
OUT
= 1V step
3
V
CC
-
0.25V
19
90
MAX9812L/MAX9813L
MAX9812H/MAX9813H
I
BIAS
= 0
SHDN
= GND
MAX9812L/MAX9813L
MAX9812H/MAX9813H
1.35
2.25
Inferred from
PSRR test
2.7
4.5
230
0.1
1.5
2.5
85
20
100
100
100
90
V
CC
-
0.1
V
CC
-
0.1V
0.1
0.1
12
400
50
0.5
1
0.25
24
mA
kHz
pF
Ω
V/µs
V
dB
21
3.6
5.5
400
1
1.65
2.75
V
µA
µA
V
kΩ
dB
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
Tiny, Low-Cost, Single/Dual-Input, Fixed-Gain
Microphone Amplifiers with Integrated Bias
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= 3.3V, I
BIAS
= 500µA (MAX9812L/MAX9813L), V
CC
= 5V, I
BIAS
= 800µA (MAX9812H/MAX9813H), GND = 0V, R
L
= open,
SHDN
= V
CC
, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
Amplifier Input Voltage-Noise
Density
Total Integrated Input Noise
Off-Isolation
SYMBOL
e
n
V
n
CONDITIONS
Inputs at AC GND
f = 1kHz
MIN
TYP
40
5
75
60
0.04
%
VOUT = 4V
P-P
(H version)
2.1
3.6
70
0.015
MAX
UNITS
nV/√Hz
µV
RMS
dB
MAX9812/MAX9813
22Hz to 22kHz BW, inputs at AC GND
Input referred, MAX9813
only
f = 1kHz, R
L
= 10kΩ to
V
CC
/2, BW = 22Hz to
22kHz
1kHz
10kHz
VOUT = 1V
P-P
(L version)
Total Harmonic Distortion Plus
Noise
BIAS
Bias Output Voltage Range
Bias Output Resistance
Power-Supply Rejection Ratio
(V
CC
to BIAS)
BIAS Current Limit
BIAS Capacitive-Load Stability
Total Integrated BIAS Noise
DIGITAL INPUTS (SHDN, IN1/IN2)
Logic-Low Threshold
Logic-High Threshold
Logic Input Current
Shutdown Enable Time
Shutdown Disable Time
IN1/IN2 Select Time
THD+N
V
BIAS
R
BIAS
MAX9812L/MAX9813L
MAX9812H/MAX9813H
DC, T
A
= +25°C
2.30
4.0
0.1
80
80
75
55
2.55
4.4
V
Ω
PSRR
BIAS
f = 217Hz
f = 1kHz
f = 10kHz
BIAS short to GND
No sustained oscillations
22Hz to 22kHz BW
5
dB
I
BIAS_SC
C
BIAS
V
n
V
IL
V
IH
I
IN
t
SHDN_ON
t
SHDN_OFF
t
SEL
22
50
29
50
mA
pF
µV
RMS
0.8
2.0
SHDN
= GND or V
CC
95% of settled value
10
50
10
±1
V
V
µA
ms
µs
µs
Note 1:
All specifications are 100% tested at T
A
= +25°C. Temperature limits are guaranteed by design.
_______________________________________________________________________________________
3
Tiny, Low-Cost, Single/Dual-Input, Fixed-Gain
Microphone Amplifiers with Integrated Bias
MAX9812/MAX9813
Typical Operating Characteristics
(V
CC
= 3.3V (MAX9812L/MAX9813L), V
CC
= 5V (MAX9812H/MAX9813H), GND = 0V, R
L
= 10kΩ to V
CC
/2,
SHDN
= V
CC
, T
A
= +25°C,
unless otherwise noted.)
GAIN vs. FREQUENCY
MAX9812 toc01
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-110
-120
-130
-140
-150
10
100
1k
FREQUENCY (Hz)
MAX9812 toc02
POWER-SUPPLY REJECTION RATIO
(V
CC
TO BIAS) vs. FREQUENCY
-10
-20
PSRR (V
CC
TO BIAS) (dB)
-30
-40
-50
-60
-70
-80
-90
-100
V
RIPPLE
= 200mV
P-P
MAX9812 toc03
MAX9812 toc06
40
30
20
10
0
-10
-20
10
R
L
= OPEN
V
OUT
= 10mV
P-P
0
V
RIPPLE
= 200mV
P-P
INPUT REFERRED
OUTPUT VOLTAGE GAIN (dB)
100
1k
10k
100k
1M
10M
PSRR (dB)
10k
100k
10
100
1k
FREQUENCY (Hz)
10k
100k
FREQUENCY (Hz)
SUPPLY CURRENT
vs. TEMPERATURE
MAX9812 toc04
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX9812 toc05
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
0.15
SHUTDOWN SUPPLY CURRENT (µA)
0.14
0.13
0.12
0.11
0.10
0.09
0.08
0.07
0.06
0.05
250
245
240
SUPPLY CURRENT (µA)
235
230
225
220
215
210
205
200
-40 -25 -10
5
20
35
50
65
80
TEMPERATURE (°C)
MAX9812L
MAX9812H
300
280
260
SUPPLY CURRENT (µA)
240
220
200
180
160
140
120
100
MAX9812H
MAX9812L
2.0 2.4 2.8 3.2 3.6 4.0 4.4 4.8 5.2 5.6 6.0
SUPPLY VOLTAGE (V)
-40 -25 -10
5
20
35
50
65
80
TEMPERATURE (°C)
V
BIAS
vs. TEMPERATURE
2.33
2.32
V
BIAS
(L VERSION) (V)
2.31
2.30
MAX9812H
MAX9812 toc07
V
BIAS
vs. I
BIAS
4.03
4.02
2.3001
V
BIAS
(H VERSION) (V)
V
BIAS
(L VERSION) (V)
4.01
4.00
3.99
MAX9812L
2.3002
MAX9812 toc08
4.0002
2.3000
4.0000
2.2999
MAX9812H
2.2998
3.9999
MAX9812L
2.29
2.28
2.27
-40 -25 -10
5
20
35
50
65
80
TEMPERATURE (°C)
3.98
3.97
3.96
2.2997
0
3.9998
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
I
BIAS
(mA)
4
_______________________________________________________________________________________
V
BIAS
(H VERSION) (V)
4.0001
Tiny, Low-Cost, Single/Dual-Input, Fixed-Gain
Microphone Amplifiers with Integrated Bias
Typical Operating Characteristics (continued)
(V
CC
= 3.3V (MAX9812L/MAX9813L), V
CC
= 5V (MAX9812H/MAX9813H), GND = 0V, R
L
= 10kΩ to V
CC
/2,
SHDN
= V
CC
, T
A
= +25°C,
unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
MAX9812 toc09
MAX9812/MAX9813
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT AMPLITUDE
H VERSION
BW = 22Hz TO 22kHz
1
THD+N (%)
f = 10kHz
0.1
MAX9812 toc10
1
BW = 22Hz TO 22kHz
10
0.1
THD+N (%)
V
OUT
= 1V
RMS
R
L
= 2kΩ
0.01
V
OUT
= 1V
RMS
R
L
= 10kΩ
0.001
10
100
1k
FREQUENCY (Hz)
10k
100k
0.01
f = 100Hz
f = 1kHz
0.001
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
OUTPUT AMPLITUDE (V
RMS
)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT AMPLITUDE
MAX9812 toc11
INPUT-REFERRED NOISE vs. FREQUENCY
INPUTS AT AC GND
INPUT-REFERRED NOISE (nV/√Hz)
70
MAX9812 toc12
100
L VERSION
BW = 22Hz TO 22kHz
10
f = 1kHz
f = 10kHz
100
THD+N (%)
1
50
0.1
30
0.01
f = 100Hz
0.001
0
0.5
1.0
1.5
OUTPUT AMPLITUDE (V
RMS
)
10
10
100
1k
FREQUENCY (Hz)
10k
100k
BIAS NOISE vs. FREQUENCY
MAX9812 toc13
OFF-ISOLATION vs. FREQUENCY
0
-10
-20
CROSSTALK (dB)
-30
-40
-50
-60
-70
-80
-90
IN1 TO OUT WITH
IN2 SELECTED
MAX9813
V
IN1
= 100mV
RMS
MAX9812 toc14
10,000
10
BIAS NOISE (nV/√Hz)
1000
100
10
10
100
1k
FREQUENCY (Hz)
10k
100k
-100
10
100
1k
FREQUENCY (Hz)
10k
100k
_______________________________________________________________________________________
5
