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 out-
puts, an industry-leading 100dB power-supply rejection
ratio, and a very low 0.015% THD+N. Power-saving fea-
tures 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.
Applications
Notebook Computers
PDAs
Smart Phones
Digital Cameras
Video Tape Recorders
Features
oPC2001 Compliant
o100dB at 217Hz Power-Supply Rejection Ratio
oVery Low 230µA Quiescent Current
oLow 0.015% THD+N
oAvailable in Two Versions
MAX9812L/MAX9813L—2.7V to 3.6V
MAX9812H/MAX9813H—4.5V to 5.5V
oInternal Low-Noise Microphone Bias Supply
2.3V for MAX9812L/MAX9813L
4.0V for MAX9812H/MAX9813H
o100nA Low-Power Shutdown Mode
oRail-to-Rail Outputs
o20dB Fixed Gain
oAvailable in Tiny 6-Pin SC70 (2mm x 2.1mm) and
8-Pin SOT23 (3mm x 3mm) Packages
oExtended Temperature Range -40°C to +85°C
19-2840; Rev 3; 4/14
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
MAX9812/MAX9813
Tiny, Low-Cost, Single/Dual-Input, Fixed-Gain
Microphone Amplifiers with Integrated Bias
Ordering Information
Pin Configurations, Selector Guide, and Typical Operating
Circuits appear at end of data sheet.
PART TEMP RANGE
PIN-
PACKAGE VCC (V)
MAX9812LEXT+T -40°C to +85°C 6 SC70 2.7 to 3.6
MAX9812HEXT+T -40°C to +85°C 6 SC70 4.5 to 5.5
MAX9813LEKA+T -40°C to +85°C 8 SOT23 2.7 to 3.6
MAX9813HEKA+T -40°C to +85°C 8 SOT23 4.5 to 5.5
MAX9812
20dB
REFERENCE
2.3V (L VERSION)
4.0V (H VERSION)
IN
BIAS
OUT
SHDN
VCC
GND
MAX9813
20dB
IN1/IN2
REFERENCE
2.3V (L VERSION)
4.0V (H VERSION)
IN2
IN1
BIAS
OUT
SHDN
VCC
GND
Simplified Block Diagrams
+
Denotes a lead(Pb)-free/RoHS-compliant package.
2Maxim Integrated
MAX9812/MAX9813
Tiny, Low-Cost, Single/Dual-Input, Fixed-Gain
Microphone Amplifiers with Integrated Bias
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC = 3.3V, IBIAS = 500µA (MAX9812L/MAX9813L), VCC = 5V, IBIAS = 800µA (MAX9812H/MAX9813H), VGND = 0V, RL= open,
SHDN = VCC, TA= TMIN to TMAX, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
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.
(All voltages referenced to GND.)
VCC ........................................................................-0.3V to +6.0V
All Other Pins..............................................-0.3V to (VCC + 0.3V)
Continuous Current (IN, SHDN, IN1, IN2, IN1/IN2)...........±20mA
OUT, BIAS Short-Circuit Duration (to GND or VCC) ...Continuous
Continuous Power Dissipation (TA= +70°C)
SC70 (derate 3.1mW/°C above +70°C) .......................245mW
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
Soldering Temperature (reflow) .......................................+260°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
GENERAL
MAX9812L/MAX9813L 2.7 3.6
Supply Voltage Range VCC MAX9812H/MAX9813H
Inferred from
PSRR test 4.5 5.5 V
Supply Current ICC IBIAS = 0A 230 400 µA
Shutdown Supply Current ICC_SHDN SHDN = GND 0.1 1 µA
MAX9812L/MAX9813L 1.35 1.5 1.65
Amplifier Output Bias Voltage VOUT_DC MAX9812H/MAX9813H 2.25 2.5 2.75 V
Input Resistance RIN 85 kΩ
Voltage Gain AV19 20 21 dB
DC 90 100
f = 217Hz 100
f = 1kHz 100
Power-Supply Rejection Ratio PSRROUT Input referred, TA = +25°C
f = 10kHz 90
dB
RL = 10kΩ to VCC/2 VCC -
0.1
VOH
RL = 1kΩ to VCC/2 VCC -
0.25V
VCC -
0.1V
RL = 10kΩ to VCC/2 0.1
Output Voltage Swing
VOL RL = 1kΩ to VCC/2 0.1 0.25
V
Output Short-Circuit Current IOUT_SC Sinking or sourcing 3 12 24 mA
Small-Signal -3dB Bandwidth BW VOUT = 10mVP-P 400 kHz
Output Capacitive-Load Stability CLNo sustained oscillations 50 pF
Output Impedance ZOUT f = 1kHz 0.5 Ω
Output Slew Rate SR VOUT = 1V step 1 V/µs
3
Maxim Integrated
MAX9812/MAX9813
Tiny, Low-Cost, Single/Dual-Input, Fixed-Gain
Microphone Amplifiers with Integrated Bias
ELECTRICAL CHARACTERISTICS (continued)
(VCC = 3.3V, IBIAS = 500µA (MAX9812L/MAX9813L), VCC = 5V, IBIAS = 800µA (MAX9812H/MAX9813H), VGND = 0V, RL= open,
SHDN = VCC, TA= TMIN to TMAX, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
Note 1: All specifications are 100% tested at TA= +25°C. Temperature limits are guaranteed by design.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Amplifier Input Voltage-Noise
Density enInputs at AC GND f = 1kHz 40 nV/√Hz
Total Integrated Input Noise Vn22Hz to 22kHz BW, inputs at AC GND 5 µVRMS
1kHz 75
Off-Isolation Input referred, MAX9813
only 10kHz 60 dB
VOUT = 1VP-P
(L version) 0.04
Total Harmonic Distortion Plus
Noise THD+N
f = 1kHz, RL = 10kΩ to
VCC/2, BW = 22Hz to
22kHz VOUT = 4VP-P
(H version) 0.015
%
BIAS
MAX9812L/MAX9813L 2.1 2.30 2.55
Bias Output Voltage Range VBIAS MAX9812H/MAX9813H 3.6 4.0 4.4 V
Bias Output Resistance RBIAS 0.1 Ω
DC, TA = +25°C 70 80
f = 217Hz 80
f = 1kHz 75
Power-Supply Rejection Ratio
(VCC to BIAS) PSRRBIAS
f = 10kHz 55
dB
BIAS Current Limit IBIAS_SC BIAS short to GND 5 22 50 mA
BIAS Capacitive-Load Stability CBIAS No sustained oscillations 50 pF
Total Integrated BIAS Noise Vn22Hz to 22kHz BW 29 µVRMS
DIGITAL INPUTS (SHDN, IN1/IN2)
Logic-Low Threshold VIL 0.8 V
Logic-High Threshold VIH 2.0 V
Logic Input Current IIN SHDN = GND or VCC ±1µA
Shutdown Enable Time tSHDN_ON 95% of settled value 10 ms
Shutdown Disable Time tSHDN_OFF 50 µs
IN1/IN2 Select Time tSEL 10 µs
Typical Operating Characteristics
(VCC = 3.3V (MAX9812L/MAX9813L), VCC = 5V (MAX9812H/MAX9813H), VGND = 0V, RL= 10kΩto VCC/2, SHDN = VCC, TA= +25°C,
unless otherwise noted.)
-20
0
-10
20
10
30
40
10 1k 10k100 100k 1M 10M
GAIN vs. FREQUENCY
MAX9812 toc01
FREQUENCY (Hz)
OUTPUT VOLTAGE GAIN (dB)
RL = OPEN
VOUT = 10mVP-P
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX9812 toc02
FREQUENCY (Hz)
PSRR (dB)
10k1k10010 100k
-150
-80
-90
-100
-110
-120
-130
-140
-60
-70
-40
-50
-30
-10
-20
0
VRIPPLE = 200mVP-P
INPUT REFERRED
POWER-SUPPLY REJECTION RATIO
(VCC TO BIAS) vs. FREQUENCY
MAX9812 toc03
FREQUENCY (Hz)
PSRR (VCC TO BIAS) (dB)
10k1k100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
-100
10 100k
VRIPPLE = 200mVP-P
200
210
205
220
215
230
225
235
245
240
250
-40 -10 5 20-25 35 50 65 80
SUPPLY CURRENT
vs. TEMPERATURE
MAX9812 toc04
TEMPERATURE (°C)
SUPPLY CURRENT (μA)
MAX9812H
MAX9812L
100
140
120
180
160
220
200
240
280
260
300
2.0 2.8 3.2 3.62.4 4.0 4.4 4.8 5.65.2 6.0
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX9812 toc05
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (μA)
MAX9812L
MAX9812H
0.05
0.07
0.06
0.09
0.08
0.11
0.10
0.12
0.14
0.13
0.15
-40 -10 5 20-25 35 50 65 80
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
MAX9812 toc06
TEMPERATURE (°C)
SHUTDOWN SUPPLY CURRENT (μA)
2.27
2.28
2.29
2.30
2.31
2.32
2.33
-40 -10-25 5 20 35 50 65 80
VBIAS vs. TEMPERATURE
MAX9812 toc07
TEMPERATURE (°C)
VBIAS (L VERSION) (V)
3.97
3.98
3.99
4.00
4.01
4.02
4.03
3.96
VBIAS (H VERSION) (V)
MAX9812H
MAX9812L
2.2997
2.2998
2.2999
2.3000
2.3001
2.3002
0 0.8 1.00.4 0.60.2 1.2 1.4 1.6 1.8 2.0
VBIAS vs. IBIAS
MAX9812 toc08
IBIAS (mA)
VBIAS (L VERSION) (V)
MAX9812H
MAX9812L
3.9998
3.9999
4.0000
4.0001
4.0002
VBIAS (H VERSION) (V)
4Maxim Integrated
MAX9812/MAX9813
Tiny, Low-Cost, Single/Dual-Input, Fixed-Gain
Microphone Amplifiers with Integrated Bias
Typical Operating Characteristics (continued)
(VCC = 3.3V (MAX9812L/MAX9813L), VCC = 5V (MAX9812H/MAX9813H), VGND = 0V, RL= 10kΩto VCC/2, SHDN = VCC, TA= +25°C,
unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT AMPLITUDE
MAX9812 toc10
OUTPUT AMPLITUDE (VRMS)
THD+N (%)
1.81.61.41.21.00.80.60.40.2
0.01
0.1
1
10
0.001
0 2.0
H VERSION
BW = 22Hz TO 22kHz
f = 10kHz
f = 1kHz
f = 100Hz
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT AMPLITUDE
MAX9812 toc11
OUTPUT AMPLITUDE (VRMS)
THD+N (%)
1.00.5
0.01
0.1
1
100
10
0.001
0 1.5
f = 10kHz
f = 100Hz
f = 1kHz
L VERSION
BW = 22Hz TO 22kHz
100
50
30
70
10
10 10k 100k
FREQUENCY (Hz)
INPUT-REFERRED NOISE (nV/√Hz)
100
INPUT-REFERRED NOISE vs. FREQUENCY
INPUTS AT AC GND
1k
MAX9812 toc12
BIAS NOISE vs. FREQUENCY
MAX9812 toc13
FREQUENCY (Hz)
BIAS NOISE (nV/√Hz)
10k1k100
100
1000
10,000
10
10 100k
OFF-ISOLATION vs. FREQUENCY
MAX9812 toc14
FREQUENCY (Hz)
CROSSTALK (dB)
10k1k100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
10
-100
10 100k
MAX9813
VIN1 = 100mVRMS
IN1 TO OUT WITH
IN2 SELECTED
5
Maxim Integrated
MAX9812/MAX9813
Tiny, Low-Cost, Single/Dual-Input, Fixed-Gain
Microphone Amplifiers with Integrated Bias
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
MAX9812 toc09
FREQUENCY (Hz)
THD+N (%)
10k1k100
0.01
0.1
1
0.001
10 100k
VOUT = 1VRMS
RL = 2kΩ
BW = 22Hz TO 22kHz
VOUT = 1VRMS
RL = 10kΩ
6Maxim Integrated
MAX9812/MAX9813
Tiny, Low-Cost, Single/Dual-Input, Fixed-Gain
Microphone Amplifiers with Integrated Bias
2μs/div
OUTPUT OVERDRIVEN
OUT
1V/div
MAX9812 toc19
IN
500mV/div
Typical Operating Characteristics (continued)
(VCC = 3.3V (MAX9812L/MAX9813L), VCC = 5V (MAX9812H/MAX9813H), VGND = 0V, RL= 10kΩto VCC/2, SHDN = VCC, TA= +25°C,
unless otherwise noted.)
1ms/div
OUT-OF-SHUTDOWN WAVEFORM
INPUT UNCONNECTED
MAX9812 toc17
OUT
2V/div
BIAS
2V/div
SHDN
2V/div
100μs/div
MAX9813
SWITCHING BETWEEN TWO INPUTS
1V/div
MAX9812 toc18
2V/div
OUT
IN1/IN2
IN2 = 200mVP-P AT 20kHz
IN1 = 100mVP-P AT 10kHz
1μs/div
SMALL-SIGNAL PULSE RESPONSE
(RL = OPEN, CL = 10pF)
IN
5mV/div
MAX9812 toc15
OUT
50mV/div
2μs/div
LARGE-SIGNAL PULSE RESPONSE
(RL = OPEN, CL = 10pF)
IN
100mV/div
MAX9812 toc16
OUT
1V/div
0V
7
Maxim Integrated
MAX9812/MAX9813
Tiny, Low-Cost, Single/Dual-Input, Fixed-Gain
Microphone Amplifiers with Integrated Bias
Pin Description
Detailed Description
The MAX9812_/MAX9813_ are low-power fixed-gain
microphone amplifiers available in a single- or dual-
input configuration. The gain is set at 10V/V (20dB) with
a 400kHz, -3dB bandwidth. They also feature a low-
noise, integrated microphone input bias voltage.
Single/Dual Input
The MAX9812L/MAX9812H are single-input amplifiers
and the MAX9813L/MAX9813H are dual-input ampli-
fiers. All devices typically have an input impedance of
85kΩ. The inputs to the dual version are controlled
through a fast 2:1 mux, selectable through the IN1/IN2
pin. Driving IN1/IN2 high selects IN1 and driving the
IN1/IN2 low selects IN2. IN1/IN2 is designed to be dri-
ven by a logic high of ≥2V and a logic low
≤0.8V. The IN1/IN2 has a 10µs switching time from one
channel to the other.
PC2001 Low-Noise Microphone BIAS
The MAX9812_/MAX9813_ provide a low-noise voltage
BIAS designed for biasing electret condenser micro-
phone (ECM) cartridges. The BIAS output is regulated
to typically 2.3V for the MAX9812L/MAX9813L and 4V
for the MAX9812H/MAX9813H. In the single-input ver-
sion (MAX9812_), the BIAS output can source up to
1mA. In the dual-input version (MAX9813_), the BIAS
output can source up to 2mA. The MAX9812H/
MAX9813H provides a PC2001-compliant BIAS voltage.
Output Stage
The MAX9812_/MAX9813_ rail-to-rail output (OUT) typical-
ly swings to within 100mV of the rails when driving 10kΩ.
The output DC bias point is set to 1.5V for the MAX9812L/
MAX9813L and 2.5V for the MAX9812H/MAX9813H.
Shutdown Mode
SHDN controls whether the MAX9812_/MAX9813_ is
active or in shutdown mode. Driving SHDN low forces a
low-power (100nA) shutdown mode. In this mode, the
OUT pin is set to a high-impedance state and the BIAS
pin is pulled down (70kΩ). Driving SHDN high enables
the MAX9812_/MAX9813_. SHDN is a high-impedance
input and cannot be left unconnected.
Driving Capacitive Loads
The MAX9812_/MAX9813_ output can drive up to 50pF
of capacitance without sustained oscillations.
Thermal Shutdown
The thermal shutdown feature protects the
MAX9812_/MAX9813_ from destruction due to overheat-
ing caused by shorting the outputs. This protection fea-
ture causes OUT and BIAS to shut down and go high
impedance when the die temperature reaches +140°C.
The device restarts after the die temperature falls below
+120°C.
Applications Information
Power-Up
The MAX9812_/MAX9813_ output typically settles to
95% within 10ms after power-up.
Typical Application Circuit
Figure 1 shows the MAX9813H used as a preamplifier
with the MAX9760 3W audio power amplifier.
PIN
MAX9812L/
MAX9812H
MAX9813L/
MAX9813H
NAME FUNCTION
13SHDN Active-Low Shutdown Input. Connect SHDN to VCC for normal operation. Connect SHDN
to GND for shutdown. SHDN is a high-impedance input; do not leave unconnected.
2 2 GND Ground
3 1 OUT Amplifier Output
48V
CC Positive Supply. Bypass VCC to GND with a 0.1µF capacitor.
5 7 BIAS Low-Noise Microphone Bias Output. 2.3V output for MAX9812L/MAX9813L. 4V output for
MAX9812H/MAX9813H.
6 — IN Amplifier Input (MAX9812)
— 6 IN1 Amplifer Input 1 (MAX9813)
— 5 IN2 Amplifier Input 2 (MAX9813)
— 4 IN1/IN2 Input Selector. When IN1/IN2 is high, IN1 is selected. When IN1/IN2 low, IN2 is selected.
8Maxim Integrated
MAX9812/MAX9813
Tiny, Low-Cost, Single/Dual-Input, Fixed-Gain
Microphone Amplifiers with Integrated Bias
Figure 1. Typical Application Circuit
HPF
HPF
MICROCONTROLLER
CODEC
MAX9813
IN1
IN2
BIAS
OUT
MAX9760
INR2
INR1
INL2
INL1
SVDD
BIAS
1μF
0.1μF
0.68μF
0.68μF
0.68μF
0.68μF
0.047μF
0.047μF
220μF
220μF
27.4kΩ
27.4kΩ
47kΩ
10kΩ
10kΩ680kΩ
33.2kΩ
33.2kΩ
15kΩ
15kΩ
15kΩ
15kΩ
15kΩ
10kΩ1kΩ
1kΩ
15kΩ
SCL
SDA
ADD
INT
SHDN
GAINLB
GAINLA
OUTL+
OUTL-
OUTR+
GAINRA
GAINRB
OUTR-
HPS
VDD
VDD
VDD
PVDD
VDD
VCC
VDD
GND
IN1/IN2
2.2kΩ
0.1μF
0.1μF
SHDN
0.1μF
0.1μF
22kΩ
2.2kΩ
220kΩ
9
Maxim Integrated
MAX9812/MAX9813
Tiny, Low-Cost, Single/Dual-Input, Fixed-Gain
Microphone Amplifiers with Integrated Bias
MAX9812
BIAS
IN
SHDN
VCC
GND
2.2kΩ
0.1μF
MIC
OUT
VCC
0.1μF
0.1μF
5
6
2
4
3
1
VBIAS
MAX9813
BIAS
IN1/IN2
IN1
IN2
SHDN
VCC
GND
2.2kΩ2.2kΩ
0.1μF
0.1μF
MIC1
MIC2
OUT
VCC
0.1μF
0.1μF
7
6
5
4
2
8
1
3
VBIAS
Chip Information
PROCESS: BiCMOS
Typical Operating Circuits
Selector Guide
PART PIN-PACKAGE VCC (V) TOP
MARK
MAX9812LEXT+T 6 SC70 2.7 to 3.6 ABJ
MAX9812HEXT+T 6 SC70 4.5 to 5.5 ABK
MAX9813LEKA+T 8 SOT23 2.7 to 3.6 AEEU
MAX9813HEKA+T 8 SOT23 4.5 to 5.5 AEEV
SC70
TOP VIEW
GND
VCC
OUT
1
+
6IN
5 BIAS
SHDN
MAX9812
2
34
+
SOT23
IN1
IN2IN1/IN2
1
2
8
7
VCC
BIASGND
SHDN
OUT
3
4
6
5
MAX9813
Pin Configurations
+
Denotes a lead(Pb)-free/RoHS-compliant package.
Package Information
For the latest package outline information and land patterns (foot-
prints), go to www.maximintegrated.com/packages. Note that a
“+”, “#”, or “-” in the package code indicates RoHS status only.
Package drawings may show a different suffix character, but the
drawing pertains to the package regardless of RoHS status.
PACKAGE
TYPE
PACKAGE
CODE OUTLINE NO. LAND
PATTERN NO.
6 SC70 X6SN+1 21-0077 90-0189
8 SOT K8+1 21-0078 90-0176
MAX9812/MAX9813
Tiny, Low-Cost, Single/Dual-Input, Fixed-Gain
Microphone Amplifiers with Integrated Bias
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in
the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
10
________________________________Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000
© 2014 Maxim Integrated Products, Inc. The Maxim logo and Maxim Integrated are trademarks of Maxim Integrated Products, Inc.
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 4/03 Initial release —
1 8/12 Added lead-free description 1, 9
2 9/12 Added automotive qualified part 1
3 4/14 Removed automotive qualified part and references 1
