INMP621
Wide Dynamic Range Microphone with PDM Digital Output
APPLICATIONS
GENERAL DESCRIPTION
The INMP621*is a high sound pressure level (SPL), ultra-low
noise, low power, digital output, bottom ported
omnidirectional MEMS microphone. This microphone clips at
133 dB SPL, which is useful for clearly capturing audio in loud
environments. The INMP621 consists of a MEMS microphone
element and an impedance converter amplifier followed by a
fourth-order Σ-Δ modulator. The digital interface allows the
pulse density modulated (PDM) output of two microphones
to be time multiplexed on a single data line using a single
clock. The INMP621 is pin compatible with the INMP421 and
INMP521 microphones, providing an easy upgrade path.
The INMP621 has a high SNR of 65 dBA and sensitivity of
−46 dBFS. The INMP621 has an extended wideband frequency
response, resulting in natural sound with high intelligibility.
Low current consumption and a sleep mode at less than
5.5 µA enables long battery life for portable applications.
The INMP621 is available in a thin 4 × 3 × 1 mm surfacemount package. It is reflow solder compatible with
no sensitivity degradation.
*Protected by U.S. Patents 7,449,356; 7,825,484; 7,885,423; and 7,961,897.
Other patents are pending.
FUNCTIONAL BLOCK DIAGRAM
Tablet Computers
Notebook PCs
Smartphones
Microphone Arrays
Teleconferencing Systems
Digital Still and Video Cameras
Bluetooth Headsets
Security and Surveillance
FEATURES
High Acoustic Overload Point of 133 dB SPL
Small, Thin 4 × 3 × 1 mm Surface-Mount Package
Omnidirectional Response
Very High Signal-to-Noise Ratio (SNR): 65 dBA
Sensitivity of −46 dBFS
Extended Frequency Response from 45 Hz to >20 kHz
Low Current Consumption: 1.2 mA
Sleep Mode for Extended Battery Life: 5.5 µA
High Power Supply Rejection (PSR): −100 dBFS
Fourth-Order Σ-Δ Modulator
Digital Pulse Density Modulation (PDM) Output
Compatible with Sn/Pb and Pb-Free Solder Processes
RoHS/WEEE Compliant
ORDERING INFORMATION
PART
INMP621
VDD
GND
POWER
MANAGEMENT
PDM
MODULATOR
CLK
DATA
CHANNEL
SELECT
−40°C to +85°C
−40°C to +85°C
—
* – 13” Tape and Reel
† – 7” Tape and reel to be discontinued. Check with
sales@invensense.com for availability.
L/R SELECT
ADC
TEMP RANGE
INMP621ACEZ-R0*
INMP621ACEZ-R7†
EV_INMP621-FX
BOTTOM
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
+1(408) 988–7339
www.invensense.com
TOP
Document Number: DS-INMP621-00
Revision: 1.3
INMP621
TABLE OF CONTENTS
General Description ........................................................................................................................................................ 1
FUNCTIONAL BLOCK DIAGRAM ....................................................................................................................................... 1
Applications .................................................................................................................................................................... 1
Features .......................................................................................................................................................................... 1
Ordering Information ...................................................................................................................................................... 1
Table of Contents ............................................................................................................................................................ 2
Specifications .................................................................................................................................................................. 4
Table 1. Electrical Characteristics ................................................................................................................................... 4
Table 2. Timing Characteristics ....................................................................................................................................... 5
Timing Diagram ............................................................................................................................................................... 5
Absolute Maximum Ratings ............................................................................................................................................ 6
Table 3. Absolute Maximum Ratings .............................................................................................................................. 6
ESD Caution ..................................................................................................................................................................... 6
Soldering Profile .............................................................................................................................................................. 7
Table 4. Recommended Soldering Profile* ..................................................................................................................... 7
Pin Configurations And Function Descriptions ............................................................................................................... 8
Table 5. Pin Function Descriptions .................................................................................................................................. 8
Typical Performance Characteristics............................................................................................................................... 9
Theory Of Operation ..................................................................................................................................................... 10
PDM Data Format ......................................................................................................................................................... 10
Table 6. INMP621 Channel Setting ............................................................................................................................... 10
PDM Microphone Sensitivity ........................................................................................................................................ 11
DYNAMIC RANGE CONSIDERATIONS ............................................................................................................................ 12
Connecting PDM Microphones ..................................................................................................................................... 12
Sleep Mode ................................................................................................................................................................... 14
Start-Up Time ................................................................................................................................................................ 14
Supporting Documents ................................................................................................................................................. 15
Evaluation Board User Guide ........................................................................................................................................ 15
application Note (product Specific) .............................................................................................................................. 15
Application Notes (general) .......................................................................................................................................... 15
PCB Design And Land Pattern Layout ........................................................................................................................... 16
Alternative PCB Land Patterns ...................................................................................................................................... 17
PCB Material And Thickness ......................................................................................................................................... 17
Handling Instructions .................................................................................................................................................... 18
Pick And Place Equipment ............................................................................................................................................ 18
Reflow Solder ................................................................................................................................................................ 18
Document Number: DS-INMP621-00
Revision: 1.3
Page 2 of 21
INMP621
Board Wash ................................................................................................................................................................... 18
Outline Dimensions....................................................................................................................................................... 19
Ordering Guide ............................................................................................................................................................. 20
Revision History ............................................................................................................................................................ 20
Compliance Declaration Disclaimer .............................................................................................................................. 21
Document Number: DS-INMP621-00
Revision: 1.3
Page 3 of 21
INMP621
SPECIFICATIONS
TABLE 1. ELECTRICAL CHARACTERISTICS
(TA = −40 to 85°C, VDD = 1.8 to 3.3 V, CLK = 3.072 MHz, C LOAD = 30 pF, unless otherwise noted. All minimum and maximum
specifications are guaranteed across temperature, voltage, and clock frequency specified in Table 1 and Table 2, unless otherwise
noted. Typical specifications are not guaranteed.)
PARAMETER
PERFORMANCE
Directionality
Output Polarity
Sensitivity
Signal-to-Noise Ratio (SNR)
Equivalent Input Noise (EIN)
Acoustic Dynamic Range
Digital Dynamic Range
Frequency Response
Total Harmonic Distortion (THD)
Power Supply Rejection (PSR)
Power Supply Rejection—Swept Sine
Acoustic Overload Point
Full-Scale Acoustic Level
POWER SUPPLY
Supply Voltage (VDD)
Supply Current (IS)
Normal Mode
VDD = 1.8 V
Sleep Mode
CONDITIONS
MIN
TYP
MAX
NOTES
Omni
Input acoustic pressure vs.
output data
1kHz, 94 dB SPL
20 Hz to 20 kHz, Aweighted
20 Hz to 20 kHz, Aweighted
Derived from EIN and
acoustic overload point
Derived from EIN and fullscale acoustic level
Low frequency −3 dB point
Inverted
−48
−46
−44
dBFS
65
dBA
29
dBA SPL
104
dB
111
dB
45
Hz
High frequency −3 dB point
>20
kHz
105 dB SPL
217 Hz, 100 mV p-p square
wave superimposed on
VDD = 1.8 V, A-weighted
1 kHz sine wave
10% THD
0 dBFS output
0.35
Normal Mode
Sleep Mode
DIGITAL INPUT/OUTPUT CHARACTERISTICS
Input Voltage High (VIH)
1
dBFS
−113
133
140
dBFS
dB SPL
dB SPL
1.2
1.5
mA
µA
4
1.3
5.5
1.6
8
mA
µA
4
V
0.35 x VDD
Output Voltage Low (VOL)
ILOAD = 0.5 mA
Output DC Offset
Latency
Percent of full scale
0.7 x VDD
V
V
VDD
0
20 Hz to 20 kHz, Aweighted
3
V
Input Voltage Low (VIL)
ILOAD = 0.5 mA
2
3.63
0.65 x VDD
Output Voltage High (VOH)
1, 2
%
−100
1.62
VDD = 3.3 V
Noise Floor
UNITS
0.3 x VDD
V
3
1
kHz to output within 3 dB
of final sensitivity, power
on
Sleep Time
Wake-Up Time
INPUT
tCLKIN
T1OUTDIS
T2OUTEN
T2OUTDIS
3.072
40
DATA1 (right) driven after
falling clock edge
DATA1 (right) disabled after
rising clock edge
DATA2 (left) driven after
rising clock edge
DATA2 (left) disabled after
falling clock edge
T1OUTEN
10
1.0
Clock Frequency (CLK)
Clock Duty Cycle
OUTPUT
1
ms
270
Input clock period
µs
30
1
1000
ns
3.6
MHz
%
60
31
1
ns
5
23
31
ns
ns
5
26
ns
Note 1: The microphone operates at any clock frequency between 1.0 MHz and 3.6 MHz. Some specifications may not be guaranteed at frequencies other than
3.072 MHz.
TIMING DIAGRAM
tCLKIN
CLK
t1OUTEN
t1OUTDIS
DATA1
t2OUTDIS
DATA2
t2OUTEN
Figure 1. Pulse Density Modulated Output Timing
Document Number: DS-INMP621-00
Revision: 1.3
Page 5 of 21
INMP621
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 3. ABSOLUTE MAXIMUM RATINGS
PARAMETER
Supply Voltage (VDD)
Digital Pin Input Voltage
Sound Pressure Level
Mechanical Shock
Vibration
Operating Temperature Range
Storage Temperature Range
RATING
−0.3 V to +3.63 V
−0.3 V to (VDD) + 0.3 V or 3.63 V, whichever is less
160 dB
10,000 g
Per MIL-STD-883 Method 2007, Test Condition B
−40°C to +85°C
−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.
Document Number: DS-INMP621-00
Revision: 1.3
Page 6 of 21
INMP621
SOLDERING PROFILE
CRITICAL ZONE
TL TO TP
tP
TP
TEMPERATURE
RAMP-UP
TL
tL
TSMAX
TSMIN
tS
RAMP-DOWN
PREHEAT
t25°C TO PEAK TEMPERATURE
TIME
Figure 2. Recommended Soldering Profile Limits
TABLE 4. RECOMMENDED SOLDERING PROFILE*
PROFILE FEATURE
Average Ramp Rate (TL to TP)
Sn63/Pb37
1.25°C/sec max
Pb-Free
1.25°C/sec max
100°C
100°C
150°C
200°C
60 sec to 75 sec
1.25°C/sec
45 sec to 75 sec
183°C
60 sec to 75 sec
1.25°C/sec
~50 sec
217°C
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
Minimum Temperature
(TSMIN)
Maximum Temperature
Preheat
(TSMAX)
Time (TSMIN to TSMAX), tS
Ramp-Up Rate (TSMAX to TL)
Time Maintained Above Liquidous (tL)
Liquidous Temperature (TL)
Peak Temperature (TP)
*The reflow profile in Table 4 is recommended for board manufacturing with InvenSense MEMS microphones. All
microphones are also compatible with the J-STD-020 profile.
Document Number: DS-INMP621-00
Revision: 1.3
Page 7 of 21
INMP621
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
DATA
VDD
5
1
CLK
4
2
L/R SELECT
3
GND
Figure 3. Pin Configuration
TABLE 5. PIN FUNCTION DESCRIPTIONS
PIN
NAME
FUNCTION
1
CLK
Clock Input to Microphone
2
L/R SELECT
Left Channel or Right Channel Select:
DATA 1 (right): L/R SELECT tied to GND
DATA 2 (left): L/R SELECT tied to VDD
3
GND
Ground
4
VDD
Power Supply. For best performance and to avoid potential parasitic artifacts, place a 0.1 µF
(100 nF) ceramic type X7R capacitor between Pin 4 (VDD) and ground. Place the capacitor as
close to Pin 4 as possible.
5
DATA
Digital Output Signal (DATA1 or DATA2)
Document Number: DS-INMP621-00
Revision: 1.3
Page 8 of 21
INMP621
20
20
15
15
NORMALIZED AMPLITUDE (dB)
NORMALIZED AMPLITUDE (dB)
TYPICAL PERFORMANCE CHARACTERISTICS
10
5
0
–5
–10
–15
10
5
0
–5
–10
–15
10
100
1k
10k
FREQUENCY (Hz)
–20
11609-106
–20
10
100
1k
10k
FREQUENCY (Hz)
Figure 4. Frequency Response Mask
Figure 5. Typical Frequency Response (Measured)
0
–20
10
THD + N (%)
PSR (dBFS)
–40
–60
–80
1
–100
–120
–140
100
1k
0.1
90
10k
95
100
Figure 6. PSR vs. Frequency, 100 mV p-p Swept Sine Wave
110
115
120
125
130
135
140
Figure 7. Total Harmonic Distortion + Noise (THD+N) vs. Input SPL
0
1.0
–5
0.8
–10
130dB SPL
132dB SPL
134dB SPL
136dB SPL
138dB SPL
0.6
–15
OUTPUT LEVEL (D)
OUTPUT LEVEL (dBFS)
105
INPUT LEVEL (dB SPL)
FREQUENCY (Hz)
–20
–25
–30
–35
0.4
0.2
0
–0.2
–0.4
–40
–0.6
–45
–50
–0.8
90
100
110
120
130
140
0
INPUT LEVEL (dB SPL)
0.0004
0.0006
0.0008
TIME (Seconds)
Figure 8. Linearity
Document Number: DS-INMP621-00
Revision: 1.3
0.0002
Figure 9. Clipping Characteristics
Page 9 of 21
0.0010
INMP621
THEORY OF OPERATION
PDM DATA FORMAT
The output from the DATA pin of the INMP621 is in pulse density modulated (PDM) format. This data is the 1-bit output of a fourthorder Σ-Δ modulator. The data is encoded so that the left channel is clocked on the falling edge of CLK, and the right channel is clocked
on the rising edge of CLK. After driving the DATA signal high or low in the appropriate half frame of the CLK signal, the DATA driver of
the microphone tristates. In this way, two microphones, one set to the left channel and the other to the right, can drive a single DATA
line. See Figure 1 for a timing diagram of the PDM data format; the DATA1 and DATA2 lines shown in this figure are two halves of the
single physical DATA signal. Figure 10 shows a diagram of the two stereo channels sharing a common DATA line.
CLK
DATA2 (L)
DATA
DATA1 (R)
DATA2 (L)
DATA1 (R)
Figure 10. Stereo PDM Format
If only one microphone is connected to the DATA signal, the output is only clocked on a single edge (Figure 11). For example, a left
channel microphone is never clocked on the rising edge of CLK. In a single microphone application, each bit of the DATA signal is
typically held for the full CLK period until the next transition because the leakage of the DATA line is not enough to discharge the line
while the driver is tristated.
CLK
DATA
DATA1 (R)
DATA1 (R)
DATA1 (R)
Figure 11. Mono PDM Format
See Table 6 for the channel assignments according to the logic level on the L/R SELECT pin.
TABLE 6. INMP621 CHANNEL SETTING
L/R SELECT Pin Setting
Low (tie to GND)
High (tie to VDD)
Document Number: DS-INMP621-00
Revision: 1.3
Channel
Right (DATA1)
Left (DATA2)
Page 10 of 21
INMP621
For PDM data, the density of the pulses indicates the signal amplitude. A high density of high pulses indicates a signal near positive
full scale, and a high density of low pulses indicates a signal near negative full scale. A perfect zero (DC) audio signal shows an
alternating pattern of high and low pulses.
The output PDM data signal has a small DC offset of about 3% of full scale. A high-pass filter in the codec that is connected to the digital
microphone and does not affect the performance of the microphone typically removes this DC signal.
PDM MICROPHONE SENSITIVITY
The sensitivity of a PDM output microphone is specified with the unit dBFS (decibels relative to digital full scale). A 0 dBFS sine wave
is defined as a signal whose peak just touches the full-scale code of the digital word (see Figure 12). This measurement convention also
means that signals with a different crest factor may have an RMS level higher than 0 dBFS. For example, a full-scale square wave has an
RMS level of 3 dBFS.
This definition of a 0 dBFS signal must be understood when measuring the sensitivity of the INMP621. A 1 kHz sine wave at a
94 dB SPL acoustic input to the INMP621 results in an output signal with a −46 dBFS level. The output digital word peaks at
−46 dB below the digital full-scale level. A common misunderstanding is that the output has an RMS level of −49 dBFS; however, this is
not true because of the definition of the 0 dBFS sine wave.
1.0
0.8
DIGITAL AMPLITUDE (D)
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
TIME (ms)
Figure 12. 1 kHz, 0 dBFS Sine Wave
There is not a commonly accepted unit of measurement to express the instantaneous level, as opposed to the RMS level of the
signal, of a digital signal output from the microphone. Some measurement systems express the instantaneous level of an individual
sample in units of D, where 1.0 D is digital full scale. In this case, a −46 dBFS sine wave has peaks at 0.005 D.
Document Number: DS-INMP621-00
Revision: 1.3
Page 11 of 21
INMP621
DYNAMIC RANGE CONSIDERATIONS
The full-scale digital output (0 dBFS) of the INMP621 is mapped to an acoustic input of 140 dB SPL. The microphone clips (THD =
10%) at 133 dB SPL (see Figure 7); however, it continues to output an increasingly distorted signal above that point. The peak output
level, which is controlled by the modulator, limits at about −3 dBFS (see Figure 8).
To fully use the 111 dB digital dynamic range of the output data of the INMP621 in a design, the digital signal processor (DSP), analogto-digital converter (ADC), or codec circuit following it must be chosen carefully. The decimation filter that inputs the PDM signal from
the INMP621 must have a dynamic range sufficiently better than the dynamic range of the microphone so that the overall noise
performance of the system is not degraded. If the decimation filter has a dynamic range of 10 dB better than the microphone (121
dB), the overall system noise only degrades by 0.4 dB.
CONNECTING PDM MICROPHONES
A PDM output microphone is typically connected to a codec with a dedicated PDM input. This codec separately decodes the left and right
channels and filters the high sample rate modulated data back to the audio frequency band. This codec also generates the clock for the
PDM microphones or is synchronous with the source that is generating the clock. Figure 13 and Figure 14 show mono and stereo
connections of the INMP621 to a codec. The mono connection shows an INMP621 set to output data on the right channel. To output on
the left channel, tie the L/R SELECT pin to VDD instead of tying it to GND.
1.8V TO 3.3V
0.1µF
CODEC
VDD
INMP621
L/R SELECT
CLK
CLOCK OUTPUT
DATA
DATA INPUT
GND
Figure 13. Mono PDM Microphone (Right Channel) Connection to Codec
Document Number: DS-INMP621-00
Revision: 1.3
Page 12 of 21
INMP621
1.8 V TO 3.3 V
0.1µF
CODEC
VDD
INMP621
CLK
CLOCK OUTPUT
DATA
L/R SELECT
DATA INPUT
GND
1.8 V TO 3.3 V
0.1µF
VDD
INMP621
L/R SELECT
CLK
DATA
GND
Figure 14. Stereo PDM Microphone Connection to Codec
One microphone may be enabled while a second microphone sharing the same data line is powered down. In this case, where one
microphone is powered up and another is powered down by disabling the VDD supply or in sleep mode by reducing the frequency of
a separate clock source, the disabled microphone does not present a load to the signal on the LPM microphone’s DATA pin.
Decouple the VDD pin of the INMP621 to GND with a 0.1 µF capacitor. Place this capacitor as close to VDD as the printed circuit board
(PCB) layout allows.
Do not use a pull-up or pull-down resistor on the PDM data signal line because it can pull the signal to an incorrect state during the period
that the signal line is tri-stated.
The DATA signal does not need to be buffered in normal use when the INMP621 microphone(s) is placed close to the codec on the PCB. If
the DATA signal must be driven over a long cable (>15 cm) or other large capacitive load, a digital buffer may be required. Only use a signal
buffer on the DATA line when one microphone is in use or after the point where two microphones are connected (see
Figure 15). The DATA output of each microphone in a stereo configuration cannot be individually buffered because the two buffer
outputs cannot drive a single signal line. If a buffer is used, take care to select one with low propagation delay so that the timing of
the data connected to the codec is not corrupted.
Document Number: DS-INMP621-00
Revision: 1.3
Page 13 of 21
INMP621
INMP621
CODEC
CLOCK OUTPUT
CLK
DATA
DATA INPUT
INMP621
CLK
DATA
Figure 15. Buffered Connections Between Stereo INMP621s and a Codec
When long wires are used to connect the codec to the INMP621, a source termination resistor can be used on the clock output of the
codec instead of a buffer to minimize signal overshoot or ringing. Match the value of this resistor to the characteristic impedance of
the CLK trace on the PCB. Depending on the drive capability of the codec clock output, a buffer may still be needed, as shown in
Figure 15.
SLEEP MODE
The microphone enters sleep mode when the clock frequency falls below 1 kHz. In this mode, the microphone data output is in a high
impedance state. The current consumption in sleep mode is less than 5.5 µA.
The INMP621 enters sleep mode within 1ms of the clock frequency falling below 1 kHz. The microphone wakes up from sleep mode
and begins to output data 32,768 cycles after the clock becomes active. For a 3.072 MHz clock, the microphone starts to output data in
10.7 ms. For a 2.4 MHz clock, the microphone starts to output data in 13.7 ms. The wake-up time, as specified in Table 2, indicates the
time from when the clock is enabled to when the INMP621 outputs data within 3 dB of its settled sensitivity.
START-UP TIME
The start-up time of the INMP621 from when the clock is active is the same as the wake-up time. The microphone starts up 32,768
cycles after the clock is active.
Document Number: DS-INMP621-00
Revision: 1.3
Page 14 of 21
INMP621
SUPPORTING DOCUMENTS
For additional information, see the following documents.
EVALUATION BOARD USER GUIDE
UG-326 PDM Digital Output MEMS Microphone Evaluation Board
APPLICATION NOTE (PRODUCT SPECIFIC)
AN-0078 High Performance Digital MEMS Microphone Simple Interface to a SigmaDSP Audio Codec
APPLICATION NOTES (GENERAL)
AN-1003 Recommendations for Mounting and Connecting the Invensense, Bottom-Ported MEMS Microphones
AN-1068 Reflow Soldering of the MEMS Microphone
AN-1112 Microphone Specifications Explained
AN-1124 Recommendations for Sealing Invensense, Bottom-Port MEMS Microphones from Dust and Liquid Ingress
AN-1140 Microphone Array Beamforming
Document Number: DS-INMP621-00
Revision: 1.3
Page 15 of 21
INMP621
PCB DESIGN AND LAND PATTERN LAYOUT
The response of the INMP621 is not affected by the PCB hole size as long as the hole is not smaller than the sound port of the
microphone (0.25 mm, or 0.010 inch, in diameter). A 0.5 mm to 1 mm (0.020 inch to 0.040 inch) diameter for the hole is recommended.
Take care to align the hole in the microphone package with the hole in the PCB. The exact degree of the alignment does not affect the
microphone performance as long as the holes are not partially or completely blocked.
3.80
ø1.70
CENTER LINE
(0.30)
0.40 × 0.60 (4×)
0.35
0.90
(1.000)
(0.30)
2.80
ø1.10
(0.30)
0.70
(0.30)
(0.550)
2× R0.10
2.05
0.35
Dimensions shown in millimeters
Figure 16. Recommended PCB Land Pattern Layout
2.45
1.498 × 0.248
0.9
0.248 × 0.948 (2×)
0.398 × 0.298 (4×)
1.849
0.35
1.45
CENTER
LINE
0.7
1.000
1.525
1.849
0.248 × 1.148 (2×)
0.375
24°
1.17
24°
0.248 × 0.498 (2×)
1.498
0.205 WIDE
0.362 CUT (3×)
Dimensions shown in millimeters
Figure 17. Suggested Solder Paste Stencil Pattern Layout
Document Number: DS-INMP621-00
Revision: 1.3
Page 16 of 21
INMP621
ALTERNATIVE PCB LAND PATTERNS
The standard PCB land pattern of the INMP621 has a solid rectangle around the edge of the footprint that can make routing the
microphone signals more difficult in some board designs. This rectangle is used to improve the radio frequency (RF) immunity
performance of the INMP621; however, it is not necessary to have this full rectangle connected for electrical functionality. If a design
can tolerate reduced RF immunity, this rectangle can either be broken or removed completely from the PCB footprint. Figure 18 shows
an example PCB land pattern with no enclosing rectangle around the edge of the part, and Figure 19 shows an example PCB land
pattern with the rectangle broken on two sides so that the inner pads can be more easily routed on the PCB.
Figure 18. Example PCB Land Pattern with No Enclosing Rectangle
Figure 19. Example PCB Land Pattern with Broken Enclosing Rectangle
Note that in both of these patterns, the solid ring around the sound port is still present; this ring is needed to ground the microphone and
for acoustic performance. The pad on the package connected to this ring is ground and still needs a solid electrical connection to the PCB
ground. If a pattern like one of these two examples is used on a PCB, take care that the unconnected rectangle on the bottom of the
INMP621 is not placed directly over any exposed copper. This ring on the microphone is still at ground, and any PCB traces routed
underneath it must be properly masked to avoid short circuits.
.
PCB MATERIAL AND THICKNESS
The performance of the INMP621 is not affected by PCB thickness and can be mounted on either a rigid or flexible PCB. A flexible
PCB with the microphone can be attached directly to the device housing with an adhesive layer. This mounting method offers a reliable
seal around the sound port, while providing the shortest acoustic path for good sound quality.
Document Number: DS-INMP621-00
Revision: 1.3
Page 17 of 21
INMP621
HANDLING INSTRUCTIONS
PICK AND PLACE EQUIPMENT
The MEMS microphone can be handled using standard pick-and-place and chip shooting equipment. Take care to avoid damage to the
MEMS microphone structure as follows:
Use a standard pickup tool to handle the microphone. Because the microphone hole is on the bottom of the package, the
pickup tool can make contact with any part of the lid surface.
Do not pick up the microphone with a vacuum tool that makes contact with the bottom side of the microphone.
Do not pull air out of or blow air into the microphone port.
Do not use excessive force to place the microphone on the PCB.
REFLOW SOLDER
For best results, the soldering profile must be in accordance with the recommendations of the manufacturer of the solder paste used to
attach the MEMS microphone to the PCB. It is recommended that the solder reflow profile not exceed the limit conditions specified in
Figure 2 and Table 4.
BOARD WASH
When washing the PCB, ensure that water does not make contact with the microphone port. Do not use blow-off procedures or
ultrasonic cleaning.
Document Number: DS-INMP621-00
Revision: 1.3
Page 18 of 21
INMP621
OUTLINE DIMENSIONS
4.10
4.00
3.90
0.95 REF
3.54 REF
1.70 DIA.
0.70
0.40 × 0.60
(Pins 1, 2, 4, 5)
PIN 1
0.30 REF
0.90
2.48
REF
1
2
5
4
3
0.30 REF
3.10
3.00
2.90
1.10 DIA.
1.50
0.25 DIA.
(THRU HOLE)
R 0.10 (2 ×)
2.80
1.05 REF
TOP VIEW
1.10
1.00
0.90
2.05
REFERENCE
CORNER
0.35
0.35
0.30 REF
0.30 REF
0.72 REF
SIDE VIEW
04-19-2012-G
3.80
BOTTOM VIEW
0.24 REF
Figure 20. 5-Terminal Chip Array Small Outline No Lead Cavity [LGA_CAV]
4 mm × 3 mm Body
Dimensions shown in millimeters
PART NUMBER
PIN 1 INDICATION
621
YYXXXX
DATE CODE
LOT TRACEABILITY CODE
Figure 21. Package Marking Specification (Top View)
Document Number: DS-INMP621-00
Revision: 1.3
Page 19 of 21
INMP621
ORDERING GUIDE
PART1
INMP621ACEZ-R0*
TEMP RANGE
−40°C to +85°C
PACKAGE
5-Terminal LGA_CAV
QUANTITY
5,000
INMP621ACEZ-R7†
−40°C to +85°C
5-Terminal LGA_CAV
1,000
EV_INMP621-FX
—
Flexible Evaluation Board —
* – 13” Tape and Reel
† – 7” Tape and reel is to be discontinued. Check with sales@invensense.com for availability.
1
Z = RoHS Compliant Part
REVISION HISTORY
REVISION DATE
REVISION
DESCRIPTION
02/06/2014
1.0
Initial Release
05/21/2014
1.1
Updated Compliance Disclaimer
01/05/2015
1.2
09/04/2019
1.3
Document Number: DS-INMP621-00
Revision: 1.3
Updated ESD caution heading, font size; updated
Connecting PDM Microphones section
Updated “Table 4: Recommended Soldering Profile” –
Corrected typo for Maximum Temperature (TSMAX)
Page 20 of 21
INMP621
COMPLIANCE DECLARATION DISCLAIMER
InvenSense believes the environmental and other compliance information given in this document to be correct but cannot
guarantee accuracy or completeness. Conformity documents substantiating the specifications and component characteristics are on
file. InvenSense subcontracts manufacturing and the information contained herein is based on data received from vendors and
suppliers, which has not been validated by InvenSense.
This information furnished by InvenSense is believed to be accurate and reliable. However, no responsibility is assumed by
InvenSense for its use, or for any infringements of patents or other rights of third parties that may result from its use. Specifications
are subject to change without notice. InvenSense reserves the right to make changes to this product, including its circuits and
software, in order to improve its design and/or performance, without prior notice. InvenSense makes no warranties, neither
expressed nor implied, regarding the information and specifications contained in this document. InvenSense assumes no
responsibility for any claims or damages arising from information contained in this document, or from the use of products and
services detailed therein. This includes, but is not limited to, claims or damages based on the infringement of patents, copyrights,
mask work and/or other intellectual property rights.
Certain intellectual property owned by InvenSense and described in this document is patent protected. No license is granted by
implication or otherwise under any patent or patent rights of InvenSense. This publication supersedes and replaces all information
previously supplied. Trademarks that are registered trademarks are the property of their respective companies. InvenSense sensors
should not be used or sold in the development, storage, production or utilization of any conventional or mass-destructive weapons
or for any other weapons or life threatening applications, as well as in any other life critical applications such as medical equipment,
transportation, aerospace and nuclear instruments, undersea equipment, power plant equipment, disaster prevention and crime
prevention equipment.
©2014 InvenSense, Inc. All rights reserved. InvenSense, MotionTracking, MotionProcessing, MotionProcessor, MotionFusion,
MotionApps, DMP, AAR, and the InvenSense logo are trademarks of InvenSense, Inc. Other company and product names may be
trademarks of the respective companies with which they are associated.
©2014 InvenSense, Inc. All rights reserved.
Document Number: DS-INMP621-00
Revision: 1.3
Page 21 of 21
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