InvenSense INMP441 User manual

INMP441
Omnidirectional Microphone with Bottom Port and I2S Digital Output
GENERAL DESCRIPTION
The INMP441 is a high-performance, low power, digital-output,
omnidirectional MEMS microphone with a bottom port. The
complete INMP441 solution consists of a MEMS sensor, signal
conditioning, an analog-to-digital converter, anti-aliasing filters,
power management, and an industry-standard 24-bit I²S interface.
The I²S interface allows the INMP441 to connect directly to digital
processors, such as DSPs and microcontrollers, without the need
for an audio codec in the system.
The INMP441 has a high SNR, making it an excellent choice for
near field applications. The INMP441 has a flat wideband
frequency response, resulting in natural sound with high
intelligibility.
The INMP441 is available in a thin 4.72 × 3.76 × 1 mm surface-
mount package. It is reflow- solder compatible with no sensitivity
degradation. The INMP441 is halide free.
*Protected by U.S. Patents 7,449,356; 7,825,484; 7,885,423; and 7,961,897.
Other patents are pending.
APPLICATIONS
•Teleconferencing Systems
•Remote Controls
•Gaming Consoles
•Mobile Devices
•Laptops
•Tablets
•Security Systems
FEATURES
•Digital I²S Interface with High-Precision 24-Bit Data
•High SNR of 61 dBA
•High Sensitivity of -26 dBFS
•Flat Frequency Response from 60 Hz to 15 kHz
•Low Current Consumption of 1.4 mA
•High PSR of -75 dBFS
•Small 4.72 × 3.76 × 1 mm Surface-Mount Package
•Compatible with Sn/Pb and Pb-Free Solder Processes
•RoHS/WEEE Compliant
FUNCTIONAL BLOCK DIAGRAM ORDERING INFORMATION
PART
TEMP RANGE
INMP441ACEZ-R0*
−40°C to +85°C
INMP441ACEZ-R7†
−40°C to +85°C
EV_INMP441
—
EV_INMP441-FX
—
* – 13” Tape and Reel
† – 7” Tape and reel to be discontinued. Contact [email protected] for
availability.
INMP441
ADC
POWER
MANAGEMENT
SCK
SD
WS
GND GND GND
VDD
FILTER I2S
SERIAL
PORT
HARDWARE
CONTROL
L/R
CHIPEN
BOTTOM
TOP
InvenSense reserves the right to change the detail
specifications as may be required to permit improvements
in the design of its products.
InvenSense Inc.
1745 Technology Drive, San Jose, CA 95110 U.S.A
[phone]
www.invensense.com
Document Number: DS-INMP441-00
Revision: 1.1
Rev Date: 05/21/2014

INMP441
TABLE OF CONTENTS
General Description ................................................................................................................................................... 1
Applications ............................................................................................................................................................... 1
Features ..................................................................................................................................................................... 1
Functional Block Diagram .......................................................................................................................................... 1
Ordering Information................................................................................................................................................. 1
Table of Contents.............................................................................................................................................................. 2
Specifications .................................................................................................................................................................... 4
Table 1. Electrical Characteristics .............................................................................................................................. 4
Table 2. I2S Digital Input/Output Characteristics ....................................................................................................... 5
Table 3. Serial Data Port Specifications ..................................................................................................................... 5
Timing Diagram.......................................................................................................................................................... 5
Absolute Maximum Ratings.............................................................................................................................................. 6
Table 4. Absolute Maximum Ratings ......................................................................................................................... 6
ESD Caution ............................................................................................................................................................... 6
Soldering Profile......................................................................................................................................................... 7
Table 5. Recommended Soldering Profile*................................................................................................................ 7
Pin Configurations And Function Descriptions ................................................................................................................. 8
Table 6. Pin Function Descriptions............................................................................................................................. 8
Typical Performance Characteristics................................................................................................................................. 9
Theory of Operation ....................................................................................................................................................... 10
Understanding Sensitivity........................................................................................................................................ 10
Power Management ................................................................................................................................................ 10
Normal Operation ...................................................................................................................................................10
Standby Mode......................................................................................................................................................... 10
Power-Down Mode.................................................................................................................................................10
Startup ....................................................................................................................................................................10
I²S Data Interface ..................................................................................................................................................... 11
Data Output Mode..................................................................................................................................................11
Data Word Length...................................................................................................................................................11
Data-Word Format..................................................................................................................................................11
Digital Microphone Sensitivity................................................................................................................................. 12
Synchronizing Microphones .................................................................................................................................... 13
Digital Filter Characteristics ..................................................................................................................................... 13
High-Pass Filter ........................................................................................................................................................ 13
Table 7. High Pass Filter Characteristics .................................................................................................................. 13
Low-Pass Filter ......................................................................................................................................................... 13
Applications Information ................................................................................................................................................ 15
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Document Number: DS-INMP441-00
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INMP441
Power-Supply Decoupling........................................................................................................................................ 15
Supporting Documents ................................................................................................................................................... 16
Evaluation Board User Guide................................................................................................................................... 16
Application Notes (Product Specific) ....................................................................................................................... 16
Application Notes (General) .................................................................................................................................... 16
PCB Design And Land Pattern Layout ............................................................................................................................. 17
PCB Material And Thickness .................................................................................................................................... 18
Handling Instructions...................................................................................................................................................... 18
Pick And Place Equipment ....................................................................................................................................... 18
Reflow Solder........................................................................................................................................................... 18
Board Wash.............................................................................................................................................................. 18
Outline Dimensions......................................................................................................................................................... 19
Ordering Guide ........................................................................................................................................................ 20
Revision History ....................................................................................................................................................... 20
Compliance Declaration Disclaimer ......................................................................................................................... 21
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Document Number: DS-INMP441-00
Revision: 1.1

INMP441
SPECIFICATIONS
TABLE 1. ELECTRICAL CHARACTERISTICS
(TA= −40 to 85°C, VDD = 1.8 to 3.3 V, CLK = 2.4 MHz, CLOAD = 30 pF, unless otherwise noted. All minimum and
maximum specifications are guaranteed across temperature, voltage, and clock frequency specified in Table 1, Table
2, Table 3, unless otherwise noted. Typical specifications are not guaranteed.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
NOTES
PERFORMANCE
Directionality
Omni
Sensitivity
1 kHz, 94 dB SPL
−29
−26
−23
dBFS
1
Signal-to-Noise Ratio (SNR)
20 Hz to 20 kHz, A-weighted
61
dBA
Equivalent Input Noise (EIN)
20 Hz to 20 kHz, A-weighted
33
dBA SPL
Dynamic Range
Derived from EIN and
maximum acoustic input
87 dB
Frequency Response
Low frequency −3 dB point
60
Hz
2
High frequency −3 dB point
15
kHz
Total Harmonic Distortion (THD)
105 dB SPL
3
%
Power-Supply Rejection (PSR)
217 Hz, 100 mVp-p square
wave superimposed on VDD =
1.8 V
−75 dBFS
Maximum Acoustic Input
Peak
120
dB SPL
Noise Floor
20 Hz to 20 kHz, A-weighted,
RMS
−87 dBFS
POWER SUPPLY
Supply Voltage (VDD)
1.62
3.63
V
Supply Current (IS)
VDD = 1.8 V
Normal Mode
1.4 1.6 mA
Standby 0.8 mA
Power Down 2 µA
VDD = 3.3 V
Normal Mode
2.2
2.5
mA
Standby
0.8
mA
Power Down
4.5
µA
DIGITAL FILTER
Group Delay
17.2/fS sec
fS= 48 kHz 359
µs
fS= 16 kHz 1078
µs
Pass-Band Ripple
±0.04
dB
Stop-Band Attenuation 60 dB
Pass Band 0.423 × f
S
20.3 kHz
Note 1: The peak-to-peak amplitude relative to peak-to-peak amplitude of (224 − 1.) The stimulus is a 104 dB SPL sinusoid having RMS amplitude
of 3.1623 Pa. Sensitivity is relative to 1 Pa.
Note 2: See Figure 4 and Figure 5.
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Document Number: DS-INMP441-00
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INMP441
TABLE 2. I2S DIGITAL INPUT/OUTPUT CHARACTERISTICS
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
NOTES
DIGITAL INPUT
Input Voltage High (VIH) L/R, WS, SCK 0.7 x VDD VDD V1
Input Voltage Low (VIL) L/R, WS, SCK 0 0.25 x VDD V1
SD DIGITAL INPUT
Voltage Output Low (VOL) VDD = 1.8 V, ISINK = 0.25 mA 0.1 × VDD
V
1
Voltage Output Low (VOL) VDD = 1.8 V, ISINK = 0.7 mA 0.3 × VDD
V
1
Voltage Output High (VOH) VDD = 1.8 V, I
SINK
= 0.7 mA 0.7 × VDD V1
Voltage Output High (VOH)
VDD = 1.8 V, ISINK = 0.25 mA
0.9 × VDD
V
1
Voltage Output Low (VOL) VDD = 3.3 V, ISINK = 0.5 mA
0.1 × V
DD
V1
Voltage Output Low (VOL) VDD = 3.3 V, ISINK = 1.7 mA
0.3 × V
DD
V1
Voltage Output High (VOH) VDD = 3.3 V, ISINK = 1.7 mA
0.7 × V
DD
V1
Voltage Output High (VOH) VDD = 3.3 V, ISINK = 0.5 mA
0.9 × V
DD
V1
Note 1: Limits based on characterization results; not production tested.
TABLE 3. SERIAL DATA PORT TIMING SPECIFICATIONS
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
NOTES
tSCH SCK high 50 ns
tSCL
SCK low
50
ns
t
SCP
SCK period
312
ns
f
SCK
SCK frequency
0.5
3.2
MHz
tWSS
WS setup
0
ns
tWSH
WS hold
20
ns
fWS
WS frequency
7.8
50
kHz
TIMING DIAGRAM
Figure 1. Serial Data Port Timing
SCK
WS
SD
tSCP
tSCH
tSCL tWSH tWSS
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Document Number: DS-INMP441-00
Revision: 1.1

INMP441
ABSOLUTE MAXIMUM RATINGS
Stress above those listed as Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only
and functional operation of the device at these conditions is not implied. Exposure to the absolute maximum ratings conditions for
extended periods may affect device reliability.
TABLE 4. ABSOLUTE MAXIMUM RATINGS
PARAMETER
RATING
Supply Voltage (VDD)
−0.3 V to +3.63 V
Digital Pin Input Voltage
−0.3 V to VDD + 0.3 V or 3.63 V, whichever is less
Sound Pressure Level
160 dB
Mechanical Shock
10,000 g
Vibration
Per MIL-STD-883 Method 2007, Test Condition B
Temperature Range
Biased
−40°C to +85°C
Storage
−55°C to +150°C
ESD CAUTION
ESD (electrostatic discharge) sensitive device.
Charged devices and circuit boards can
discharge without detection. Although this
product features patented or proprietary
protection circuitry, damage may occur on
devices subjected to high energy ESD.
Therefore proper ESD precautions should be
taken to avoid performance degradation or
loss of functionality.
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Document Number: DS-INMP441-00
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INMP441
SOLDERING PROFILE
Figure 2. Recommended Soldering Profile Limits
TABLE 5. RECOMMENDED SOLDERING PROFILE*
PROFILE FEATURE
Sn63/Pb37
Pb-Free
Average Ramp Rate (T
L
to T
P
)
1.25°C/sec max
1.25°C/sec max
Preheat
Minimum Temperature
(TSMIN)
100°C 100°C
Minimum Temperature
(TSMIN)
150°C 200°C
Time (TSMIN to TSMAX), tS
60 sec to 75 sec
60 sec to 75 sec
Ramp-Up Rate (TSMAX to TL)
1.25°C/sec
1.25°C/sec
Time Maintained Above Liquidous (tL)
45 sec to 75 sec
~50 sec
Liquidous Temperature (T
L
) 183°C 217°C
Peak Temperature (T
P
)
215°C +3°C/−3°C 260°C +0°C/−5°C
Time Within +5°C of Actual Peak
Temperature (tP)
20 sec to 30 sec 20 sec to 30 sec
Ramp-Down Rate 3°C/sec max
3°C/sec max
Time +25°C (t25°C) to Peak Temperature 5 min max
5 min max
*The reflow profile in Table 5 is recommended for board manufacturing with InvenSense MEMS microphones. All microphones are
also compatible with the J-STD-020 profile.
tP
tL
t25°C TO PEAK TEMPERATURE
tS
PREHEAT
CRITICALZONE
T
L
TO T
P
TEMPERATURE
TIME
RAMP-DOWN
RAMP-UP
T
SMIN
T
SMAX
T
P
T
L
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Document Number: DS-INMP441-00
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INMP441
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
Figure 3. Pin Configuration
TABLE 6. PIN FUNCTION DESCRIPTIONS
PIN NAME FUNCTION
1
SCK
Serial-Data Clock for I²S Interface
2 SD
Serial-Data Output for I²S Interface. This pin tri-states when not actively driving the
appropriate output channel. The SD trace should have a 100 kΩ pulldown resistor to
discharge the line during the time that all microphones on the bus have tri-stated their
outputs.
3 WS Serial Data-Word Select for I²S Interface
4 L/R Left/Right Channel Select. When set low, the microphone outputs its signal in the left channel
of the I²S frame. When set high, the microphone outputs its signal in the right channel.
5 GND Ground. Connect to ground on the PCB.
6 GND Ground. Connect to ground on the PCB.
7 VDD Power, 1.8 V to 3.3 V. This pin should be decoupled to Pin 6 with a 0.1 μF capacitor.
8 CHIPEN Microphone Enable. When set low (ground), the microphone is disabled and put in power-
down mode. When set high (VDD), the microphone is enabled.
9 GND Ground. Connect to ground on the PCB.
4L/R 6GND
5GND
3WS7VDD
2SD 8CHIPEN
1SCK 9GND
BOTTOM VIEW
(Not to Scale)
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Document Number: DS-INMP441-00
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INMP441
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 4. Frequency Response Mask Figure 5. Typical Frequency Response (Measured)
Figure 6. Power-Supply Rejection (PSR) vs. Frequency
10
–10
–8
–6
–4
–2
0
2
4
6
8
50 100 10k
FREQUENCY(Hz)
SENSITIVITY (dB)
1k
10
–20
–10
0
10 100 10k
FREQUENCY(Hz)
AMPLITUDE (dB)
1k
0
–80
100 10k
FREQUENCY(Hz)
PSR (dB)
1k
–10
–20
–30
–40
–50
–60
–70
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Document Number: DS-INMP441-00
Revision: 1.1

INMP441
THEORY OF OPERATION
The INMP441 is a high-performance, low-power, digital-output, omni-directional MEMS microphone with a bottom port. The
complete INMP441 solution consists of a MEMS sensor, signal conditioning, an analog-to-digital converter, anti-aliasing filters,
power management, and an industry-standard 24-bit I²S interface.
The INMP441 complies with the TIA-920 Telecommunications Telephone Terminal Equipment Transmission Requirements for
Wideband Digital Wireline Telephones standard.
UNDERSTANDING SENSITIVITY
The casual user of digital microphones may have difficulty understanding the sensitivity specification. Unlike an analog microphone
(whose specification is easily confirmed with an oscilloscope), the digital microphone output has no obvious unit of measure.
The INMP441 has a nominal sensitivity of −26 dBFS at 1 kHz with an applied sound pressure level of 94 dB. The units are in decibels
referred to full scale. The INMP441 default full-scale peak output word is 223 − 1 (integer representation), and −26 dBFS of that scale
is (223 − 1) × 10(−26/20) = 420,426. A pure acoustic tone at 1 kHz having a 1Pa RMS amplitude results in an output digital signal whose
peak amplitude is 420,426.
Although the industry uses a standard specification of 94 dB SPL, the INMP441 test method applies a 104 dB SPL signal. The higher
sound pressure level reduces noise and improves repeatability. The INMP441 has excellent gain linearity, and the sensitivity test
result at 94 dB is derived with very high confidence from the test data.
POWER MANAGEMENT
The INMP441 has three different power states: normal operation, standby mode, and power-down mode.
Normal Operation
The microphone becomes operational 218 clock cycles (85 ms with SCK at 3.072 MHz) after initial power-up. The CHIPEN pin then
controls the power modes. The part is in normal operation mode when SCK is active and the CHIPEN pin is high.
Standby Mode
The microphone enters standby mode when the serial-data clock SCK stops and CHIPEN is high. Normal operation resumes 214 clock
cycles (5 ms with SCK at 3.072 MHz) after SCK restarts.
The INMP441 should not be transitioned from standby to power-down mode, or vice versa. Standby mode is only intended to be
entered from the normal operation state.
Power-Down Mode
The microphone enters power-down mode when CHIPEN is low, regardless of the SCK operation. Normal mode operation resumes
217 SCK clock cycles (43 ms with SCK at 3.072 MHz) after CHIPEN returns high while SCK is active.
It always takes 217 clock cycles to restart the INMP441 after VDD is applied.
It is not recommended to supply active clocks (WS and SCK) to the INMP441 while there is no power supplied to VDD. Doing this
continuously turns on ESD protection diodes, which may affect long-term reliability of the microphone.
Startup
The microphones have zero output for the first 218 SCK clock cycles (85ms with SCK at 3.072 MHz) following power-up.
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Document Number: DS-INMP441-00
Revision: 1.1