WOLFSON WM7120A

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WM7120A,WM7120AE
Top Port Analogue Silicon Microphone
DESCRIPTION
FEATURES
The WM7120A is a low-profile silicon analogue microphone.
It offers high Signal to Noise Ratio (SNR) and low power
consumption and is suited to a wide variety of consumer
applications.


- WM7120AE - SNR 57dB, Sensitivity +/-1dB
Low supply current 140µA
The WM7120A incorporates Wolfson’s proprietary
CMOS/MEMS membrane technology, offering high reliability
and high performance in a miniature, low-profile package.
The WM7120A is designed to withstand the high
temperatures associated with automated flow solder
assembly processes. (Note that conventional microphones
can be damaged by this process.)


Low profile packaging
Support for automated flow solder assembly


Analogue output
Top Port Package


1.5V to 3.7V supply
3.76mm x 2.95mm x 1.10mm Package
The WM7120AE variant offers a tighter tolerance on the
microphone sensitivity, giving reduced variation between
parts. This removes the need for in-line production
calibration of part-to-part microphone variations.
APPLICATIONS
High SNR; selectable sensitivity tolerance options
- WM7120A - SNR 57dB, Sensitivity +/-3dB


Mobile phone handsets
Portable media players


Digital still cameras
Digital video cameras


Bluetooth headsets
Portable navigation devices

Portable games consoles
BLOCK DIAGRAM
WOLFSON MICROELECTRONICS plc
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Pre-Production, April 2012, Rev 3.1
Copyright 2012 Wolfson Microelectronics plc
WM7120A
Pre-Production
TABLE OF CONTENTS
DESCRIPTION ....................................................................................................... 1 FEATURES ............................................................................................................ 1 APPLICATIONS..................................................................................................... 1 BLOCK DIAGRAM ................................................................................................ 1 TABLE OF CONTENTS ......................................................................................... 2 PIN CONFIGURATION .......................................................................................... 3 PIN DESCRIPTION ................................................................................................ 3 ORDERING INFORMATION .................................................................................. 3 ABSOLUTE MAXIMUM RATINGS ........................................................................ 4 IMPORTANT ASSEMBLY GUIDELINES .............................................................. 4 RECOMMENDED OPERATING CONDITIONS ..................................................... 4 ACOUSTIC AND ELECTRICAL CHARACTERISTICS ......................................... 5 TERMINOLOGY ............................................................................................................... 5 TYPICAL PERFORMANCE ................................................................................... 6 FREQUENCY RESPONSE .............................................................................................. 6 THD RATIO ...................................................................................................................... 6 APPLICATIONS INFORMATION .......................................................................... 7 RECOMMENDED EXTERNAL COMPONENTS .............................................................. 7 CONNECTION TO A WOLFSON AUDIO CODEC .......................................................... 8 RECOMMENDED PCB LAND PATTERNS ..................................................................... 9 PACKAGE DIMENSIONS .................................................................................... 10 IMPORTANT NOTICE ......................................................................................... 11 ADDRESS: ..................................................................................................................... 11 REVISION HISTORY ........................................................................................... 12 w
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PIN CONFIGURATION
PIN DESCRIPTION
PIN
NAME
TYPE
DESCRIPTION
1
VDD
Supply
Analogue supply
2
GND
Supply
Analogue ground
3
GND
Supply
Analogue ground
4
OUTPUT
Analogue Output
Microphone analogue output
ORDERING INFORMATION
MOISTURE
SENSITIVITY LEVEL
PEAK SOLDERING
TEMPERATURE
o
MSL2A
+260 C
o
MSL2A
+260 C
o
MSL2A
+260 C
o
MSL2A
+260 C
DEVICE
DESCRIPTION
TEMPERATURE
RANGE
WM7120AIMS/V
Standard
-40 to +100 C
WM7120AIMS/RV
Standard
(tape and reel)
-40 to +100 C
WM7120AIMSE/V
Enhanced
-40 to +100 C
WM7120AIMSE/RV
Enhanced
(tape and reel)
-40 to +100 C
o
o
o
o
Note:
Reel quantity = 5700
All devices are Pb-free and Halogen free.
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ABSOLUTE MAXIMUM RATINGS
Absolute Maximum Ratings are stress ratings only. Permanent damage to the device may be caused by continuously operating at
or beyond these limits. Device functional operating limits and guaranteed performance specifications are given under Electrical
Characteristics at the test conditions specified.
ESD Sensitive Device. This device is manufactured on a CMOS process. It is therefore generically susceptible
to damage from excessive static voltages. Proper ESD precautions must be taken during handling and storage
of this device.
Wolfson tests its package types according to IPC/JEDEC J-STD-020 for Moisture Sensitivity to determine acceptable storage
conditions prior to surface mount assembly. These levels are:
MSL1 = unlimited floor life at <30C / 85% Relative Humidity. Not normally stored in moisture barrier bag.
MSL2 = out of bag storage for 1 year at <30C / 60% Relative Humidity. Supplied in moisture barrier bag.
MSL2A = out of bag storage for 4 weeks at <30°C / 60% Relative Humidity. Supplied in moisture barrier bag.
MSL3 = out of bag storage for 168 hours at <30C / 60% Relative Humidity. Supplied in moisture barrier bag.
The Moisture Sensitivity Level for each package type is specified in Ordering Information.
CONDITION
MIN
MAX
Supply Voltage
-0.3V
+4.2V
Operating temperature range, TA
-40ºC
+100ºC
Storage temperature prior to soldering
30C max / 60% RH max
Storage temperature after soldering
-40ºC
+100ºC
IMPORTANT ASSEMBLY GUIDELINES
Do not put a vacuum over the port hole of the microphone. Placing a vacuum over the port hole can damage the device. For
information on recommended pick and place vacuum point, refer to the package dimension drawing.
Do not board wash the microphone after a re-flow process. Board washing and the associated cleaning agents can damage
the device. Do not expose to ultrasonic cleaning methods.
Do not use a vapour phase re-flow process. The vapour can damage the device.
Please refer to application note WAN_0273 for further assembly and handling guidelines.
RECOMMENDED OPERATING CONDITIONS
SYMBOL
MIN
Analogue Supply Range
PARAMETER
VDD
1.5
Ground
GND
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TYP
0
MAX
UNIT
3.7
V
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ACOUSTIC AND ELECTRICAL CHARACTERISTICS
Test Conditions: VDD=2.1V, 1kHz test signal, TA = 25°C
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
Sensitivity (WM7120A)
S
94dB SPL
-45
Sensitivity (WM7120AE)
S
94dB SPL
-43
Directivity
TYP
MAX
UNIT
-42
-39
dBV
-42
-41
Omni-directional
Acoustic Overload
No Load
dBV
131
dB SPL
dB
THD < 10%
Signal to Noise Ratio
SNR
A-Weighted
57
Total Harmonic Distortion
THD
104dB SPL
0.25
%
DR
A-Weighted,
88
dB
Dynamic Range
Noise floor to 1% THD
Frequency Response
-3dB Low Frequency
62
Hz
+3dB High Frequency
9300
Hz
Acoustic Noise Floor
A-Weighted
37
dB SPL
Electrical Noise Floor
A-Weighted
-99
dBV
100mV RMS, 217Hz
50
Power Supply Rejection Ratio
PSRR
Current Consumption
IVDD
140
Output DC Impedance
ZOUT
100
dB
190
µA
Ω
TERMINOLOGY
1.
Sensitivity (dBV) - Sensitivity is a measure of the microphone output response to the acoustic pressure of a 1kHz
94dB SPL (1Pa RMS) sine wave.
2.
Signal-to-Noise Ratio (dB) – SNR is a measure of the difference in level between the output response of a 1kHz 94dB
SPL sine wave and the idle noise output.
3.
Total Harmonic Distortion (dB) – THD is the ratio of the RMS sum of the harmonic distortion products in the specified
bandwidth (see note below) relative to the RMS amplitude of the fundamental (ie. test frequency) output.
4.
Dynamic Range (dB) – DR is the ratio of the 1% THD microphone output level (in response to a sine wave input) and
the idle noise output level.
5.
All performance measurements are carried out with 20 kHz low pass ‘brick wall’ filter and, where noted, an A-weighted
filter. Failure to use these filters will result in higher THD and lower SNR values than are found in the Acoustic and
Electrical Characteristics. The low pass filter removes out of band noise.
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TYPICAL PERFORMANCE
FREQUENCY RESPONSE
Sensitivity vs frequency
(Relative to Sensitivity @ 1KHz)
10.00
8.00
6.00
Sensitivity (dB)
4.00
2.00
0.00
‐2.00
‐4.00
‐6.00
‐8.00
‐10.00
10.0
100.0
1000.0
10000.0
Frequency (Hz)
THD RATIO
THD vs Input Sound Pressure Level
10.0
9.0
8.0
7.0
THD (%)
6.0
5.0
4.0
3.0
2.0
1.0
0.0
90.0
95.0
100.0
105.0
110.0
115.0
120.0
125.0
130.0
135.0
Input Sound Pressure Level (dB SPL)
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APPLICATIONS INFORMATION
RECOMMENDED EXTERNAL COMPONENTS
Figure 1 WM7120 Recommended External Components
A DC-blocking output capacitor is required on the OUTPUT pin, as illustrated in Figure 1. A single
capacitor is required for a single-ended connection. The capacitor must be correctly selected as it
affects the cut-off frequency of the output path. A low cut-off frequency is desirable as it means there
is no significant filtering of the audio bandwidth.
The 3dB cut-off frequency of the output path is given by the equation below, where C is the output
capacitance and R is the input resistance of the other circuit.
A typical recommended configuration, with 1uF DC-blocking capacitor and 20kΩ minimum input
circuit impedance, gives a 3dB cut-off frequency of 10Hz or less. Tantalum electrolytic capacitors are
particularly suitable for the DC-blocking components as they offer high stability in a small package
size.
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CONNECTION TO A WOLFSON AUDIO CODEC
Wolfson provides a range of audio CODECs incorporating an analogue microphone input interface;
these support connection to silicon microphones such as the WM7120A.
The recommended connection of a WM7120A silicon microphone to the WM8994 is illustrated in
Figure 2 (for single-ended mode) and Figure 3 (for pseudo-differential mode).
A DC-blocking capacitor is required, as described in the previous section. A 1µF decoupling capacitor
is also recommended; this should be positioned close to the VDD pin of the WM7120A.
Further information on the WM8994 is provided in the product datasheet, which is available from the
Wolfson website. The equivalent connections can be made to other Wolfson devices in a similar
manner.
Figure 2 WM7120A Silicon Microphone Single-ended Connection to WM8994
Figure 3 WM7120A Silicon Microphone Pseudo-differential Connection to WM8994
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RECOMMENDED PCB LAND PATTERNS
1.65 mm
Ø0.8 mm
Figure 4 Recommended Customer PCB Land Pattern
(Note that all other dimensions can be obtained from the package dimensions)
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WM7120A
PACKAGE DIMENSIONS
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MS4: PACKAGE 3.76 x 2.95 x 1.10 mm BODY
DM100.B
0.1 C
D
PIN 1 CORNER
G
M
P
R 0.35
2
1
E
2
L
PNP Vacuum
Point
3
H
3
K
R 0.45
R 0.55
0.1 C
J
N
1
4
F
TOP VIEW
BOTTOM VIEW
R 0.3
R 0.1
0.05 C
S T
-C-
A
SIDE VIEW
Symbols
MIN
A
1.03
1.10
3.76
2.95
0.65
0.65
1.65
1.18
K
1.325
1.475
L
2.60
2.70
M
3.41
3.51
D
E
F
G
H
J
1.03
3.66
2.85
0.55
0.55
1.60
Dimensions (mm)
NOM
MAX
N
P
S
T
1
1.625
2.41
0.81
0.50
2.46
0.86
0.70
0.55
0.65
1.31
0.80
NOTE
PNP Vacuum
Point
1.16
2
3
1.17
3.86
3.05
0.75
0.75
1.70
1.33
2.51
0.91
0.60
Gasket Area
0.95
NOTES:
1. THE SEATING PLANE IS REPRESENTED BY PRIMARY DATUM -C2. THE DEVIATION FROM THE SEATING PLANE DUE TO WARPAGE OR TWIST IS SPECIFIED AS MAX 50m (FLATNESS).
3. LID SHOULD BE PARALLEL TO THE SEATING PLANE ±50m.
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WM7120A
IMPORTANT NOTICE
Wolfson Microelectronics plc (“Wolfson”) products and services are sold subject to Wolfson’s terms and conditions of sale,
delivery and payment supplied at the time of order acknowledgement.
Wolfson warrants performance of its products to the specifications in effect at the date of shipment. Wolfson reserves the
right to make changes to its products and specifications or to discontinue any product or service without notice. Customers
should therefore obtain the latest version of relevant information from Wolfson to verify that the information is current.
Testing and other quality control techniques are utilised to the extent Wolfson deems necessary to support its warranty.
Specific testing of all parameters of each device is not necessarily performed unless required by law or regulation.
In order to minimise risks associated with customer applications, the customer must use adequate design and operating
safeguards to minimise inherent or procedural hazards. Wolfson is not liable for applications assistance or customer
product design. The customer is solely responsible for its selection and use of Wolfson products. Wolfson is not liable for
such selection or use nor for use of any circuitry other than circuitry entirely embodied in a Wolfson product.
Wolfson’s products are not intended for use in life support systems, appliances, nuclear systems or systems where
malfunction can reasonably be expected to result in personal injury, death or severe property or environmental damage.
Any use of products by the customer for such purposes is at the customer’s own risk.
Wolfson does not grant any licence (express or implied) under any patent right, copyright, mask work right or other
intellectual property right of Wolfson covering or relating to any combination, machine, or process in which its products or
services might be or are used. Any provision or publication of any third party’s products or services does not constitute
Wolfson’s approval, licence, warranty or endorsement thereof. Any third party trade marks contained in this document
belong to the respective third party owner.
Reproduction of information from Wolfson datasheets is permissible only if reproduction is without alteration and is
accompanied by all associated copyright, proprietary and other notices (including this notice) and conditions. Wolfson is
not liable for any unauthorised alteration of such information or for any reliance placed thereon.
Any representations made, warranties given, and/or liabilities accepted by any person which differ from those contained in
this datasheet or in Wolfson’s standard terms and conditions of sale, delivery and payment are made, given and/or
accepted at that person’s own risk. Wolfson is not liable for any such representations, warranties or liabilities or for any
reliance placed thereon by any person.
ADDRESS:
Wolfson Microelectronics plc
Westfield House
26 Westfield Road
Edinburgh
EH11 2QB
Tel :: +44 (0)131 272 7000
Fax :: +44 (0)131 272 7001
Email :: [email protected]
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REVISION HISTORY
DATE
REV
ORIGINATOR
02/05/11
2.0
JMacD
2.0
KC
2.0
JMacD
CHANGES
First release of AE variant
Added the WM7120AE
Updated the features for WM7120AE
Electrical noise floor to 101dBV
Updated the frequency response curve, the THD curves,
Updated the +3dB frequency response to 9300Hz.
Updated WM7120AE frequency response performance, and sensitivity
performance
Updated the reel quantity to 4800
Remove the 20kohms test condition.
Modified the wording for 1uF and 20kohms to ensure 10Hz low frequency
cut off
Package Diagram updated to DM058E
-
Tolerances adjusted and dimensions standardized
-
Updated tolerances for measurements G and J
Acoustic and Electrical Char: Acoustic Overload updated to 131.
06/05/11
2.0
JMacD/MR
10/05/11
2.0
MR
Updated the -3dB frequency response to 40Hz.
07/06/11
2.1
KC
Change on the pin configuration and top view.
01/07/11
2.1
JMacD/MR
Package Drawing update to reflect new pin numbering.
04/07/11
2.2
JMacD/MR
Order Code for Enhanced, 62Hz roll off updated to:
WM7120AIMSE/V
WM7120AIMSE/RV
11/10/11
2.3
JMacD
09/09/11
3.0
KC
Package Diagram changed to DM100B.
Added reference to WAN_0273.
Updated the interface CODEC to WM8994.
SNR updated to 57dB, Noise Floor to -99dBV and acoustic noise floor to
37 dB SPL.
20/02/12
3.1
KC/JMacD
Acoustic and Electrical Characteristics:
Sensitivity unit changed from dB to dBV. Updated the terminology 1.
Dynamic Range added. DR definition added
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