WM7236, WM7236E - uri=media.digikey

WM7236, WM7236E - uri=media.digikey
WM7236, WM7236E
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Low Power Bottom Port Digital Silicon Microphone
DESCRIPTION
FEATURES
The WM7236 is a low-profile digital silicon microphone,
optimised for use with low-power ‘Always-on’ voice control
applications, such as Wolfson’s Ez2 Control™ software.
•
•
The WM7236 supports two operational modes, selected
according to the applied clock frequency. ‘Hi-Fi Record’
mode offers wide dynamic range, and class-leading THD
performance. ‘Voice’ mode, selected at lower clock
frequencies, enables low current consumption, whilst
maintaining excellent SNR performance, to meet the
requirements of speech recognition algorithms.
The WM7236 incorporates Wolfson’s proprietary
CMOS/MEMS membrane technology, offering high
reliability and high performance in a miniature, low-profile
package. The WM7236 is designed to withstand the high
temperatures associated with automated flow solder
assembly processes. (Note that conventional microphones
can be damaged by this process.)
The WM7236 incorporates a high-performance ADC,
which outputs a single-bit data stream using Pulse Density
Modulation (PDM) encoding. The WM7236 supports
selectable left/right channel assignment for a two-channel
digital microphone interface, enabling efficient connection
of multiple microphones in stereo/array configurations.
The WM7236E 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.
The WM7236 and WM7236E are footprint-compatible with
other WM723X microphones, enabling direct drop-in
replacement.
BLOCK DIAGRAM
•
•
•
•
•
•
High SNR (63dB)
Low variation in sensitivity
±3dB tolerance (WM7236)
±1dB tolerance (WM7236E)
Low current consumption
10μA (Sleep)
300μA (Voice mode)
980μA (Hi-Fi Record mode)
PDM digital audio output
Stereo/array operation
Proprietary ADC technology
Reduced clock-jitter sensitivity
Low noise floor
Stable in overload condition
Bottom Port LGA Package (WM723X compatible)
1.62V to 2.0V supply
APPLICATIONS
•
•
•
•
•
•
Mobile telephone handsets
Portable computers
Portable media players
Digital cameras
Bluetooth headsets
Portable navigation devices
3D VIEW
VDD
W
WM7236
CLK
CONTROL
CHARGE
PUMP
AMP
DAT
LRSEL
ADC
CMOS MEMS
Transducer
GND
WOLFSON MICROELECTRONICS plc
CONFIDENTIAL
4.00mm x 3.00mm x 1.00mm LGA package
Preliminary Technical Data, October 2014, Rev 2.1
Copyright 2014 Wolfson Microelectronics plc
WM7236, WM7236E
CONFIDENTIAL
Preliminary Technical Data
TABLE OF CONTENTS
DESCRIPTION ................................................................................................................ 1
FEATURES ..................................................................................................................... 1
APPLICATIONS ............................................................................................................. 1
BLOCK DIAGRAM ......................................................................................................... 1
3D VIEW ......................................................................................................................... 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 ...................................................................................................................... 6
AUDIO INTERFACE TIMING .................................................................................................. 7
TYPICAL PERFORMANCE ............................................................................................ 8
APPLICATIONS INFORMATION ................................................................................... 9
RECOMMENDED EXTERNAL COMPONENTS ...................................................................... 9
OPTIMISED SYSTEM RF DESIGN ......................................................................................... 9
CONNECTION TO A WOLFSON AUDIO CODEC .................................................................. 9
PCB LAND PATTERN AND PASTE STENCIL .......................................................................10
PACKAGE DIMENSIONS ............................................................................................. 11
IMPORTANT NOTICE .................................................................................................. 12
ADDRESS: .............................................................................................................................12
REVISION HISTORY .................................................................................................... 13
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PIN CONFIGURATION
3
4
2
5
1
TOP VIEW
PIN DESCRIPTION
PIN
NAME
TYPE
DESCRIPTION
1
CLK
Digital Input
Clock input
2
LRSEL
Digital Input
Channel Select
0 = Data output following falling CLK edge
1 = Data output following rising CLK edge
Internal pull-down holds this pin at logic 0 when not connected
3
GND
Supply
4
VDD
Supply
5
DAT
Digital Output
Ground
Power Supply
PDM Data Output
ORDERING INFORMATION
DEVICE
DESCRIPTION
TEMPERATURE
RANGE
MOISTURE
SENSITIVITY LEVEL
PEAK SOLDERING
TEMPERATURE
WM7236IMS/RV
Standard
(tape and reel)
-40 to +100°C
MSL2A
+260°C
WM7236IMSE/RV
Standard
(tape and reel)
-40 to +100°C
MSL2A
+260°C
Note:
Reel quantity = 4800
All devices are Pb-free and Halogen free.
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Preliminary Technical Data
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
Supply Voltage (VDD)
Voltage range digital inputs (LRSEL, CLK)
Operating temperature range, TA
MAX
-0.3V
+4.2V
GND - 0.3V
VDD + 0.3V
-40°C
+100°C
Storage temperature prior to soldering
30°C max / 60% RH max
Storage temperature after soldering
-40°C
+100°C
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.
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 vapour phase re-flow process. The vapour can damage the device.
Please refer to application note WAN0273 (MEMS MIC Assembly and Handling Guidelines) for further assembly and handling
guidelines.
RECOMMENDED OPERATING CONDITIONS
SYMBOL
MIN
TYP
MAX
UNIT
VDD Supply Range
PARAMETER
VDD
1.62
1.8
2.0
V
Ground
GND
Clock Frequency
FCLK
6.144
MHz
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CONFIDENTIAL
0
0.3
V
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ACOUSTIC AND ELECTRICAL CHARACTERISTICS
Test Conditions: VDD=1.8V, 1kHz test signal, CLK=3.072MHz, CLOAD = 100pF, TA = 25°C, unless otherwise stated.
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
Directivity
TYP
MAX
UNIT
Omni-directional
Polarity
Positive sound pressure
Increasing density of 1s
Sensitivity (WM7236)
S
94dB SPL
-29
-26
-23
dBFS
Sensitivity (WM7236E)
S
94dB SPL
-27
-26
-25
dBFS
Hi-Fi Record Mode (CLK=3.072MHz)
Acoustic Overload
Total Harmonic Distortion
Signal to Noise Ratio
Dynamic Range
THD < 10%
THD
100dB SPL
dB SPL
1
%
118dB SPL
1
SNR
A-weighted
63
DR
A-weighted
87
dB
A-weighted
31
dB SPL
Acoustic Noise Floor
Electrical Noise Floor
Power Supply Rejection
120
dB
A-weighted
-89
dBFS
PSR
217Hz square wave,
100mV (peak-peak)
-65
dBFS
THD < 10%
120
THD
100dB SPL,
200Hz to 8kHz
Voice Mode (CLK=768kHz)
Acoustic Overload
Total Harmonic Distortion
dB SPL
1
%
118dB SPL,
200Hz to 8kHz
1
SNR
A-weighted,
200Hz to 8kHz
60
dB
DR
A-weighted,
200Hz to 8kHz
84
dB
Acoustic Noise Floor
A-weighted,
200Hz to 8kHz
34
dB SPL
Electrical Noise Floor
A-weighted,
200Hz to 8kHz
-86
dBFS
217Hz square wave,
100mV (peak-peak)
-70
dBFS
Signal to Noise Ratio
Dynamic Range
Power Supply Rejection
PSR
Frequency Response
Frequency Response
-3dB low frequency
50
+3dB high frequency
+10dB high frequency
Frequency Response Flatness
62
75
Hz
+1
dB
12000
30000
200Hz to 8kHz
-1
0.65 ×
VDD
Digital Input / Output
Input HIGH Level
VIH
VDD = 1.8V ±10%
Input LOW Level
VIL
VDD = 1.8V ±10%
Output HIGH Level
VOH
IOH = 1mA
Output LOW Level
VOL
IOL = -1mA
0.35 ×
VDD
0.9 ×
VDD
10
Input leakage
Short Circuit Output Current
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CONFIDENTIAL
-1
CLOAD
DAT connected to GND
V
V
0.1 ×
VDD
Input capacitance
Maximum load capacitance
(DAT)
V
V
pF
1
µA
200
pF
10
mA
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Test Conditions: VDD=1.8V, 1kHz test signal, CLK=3.072MHz, CLOAD = 100pF, TA = 25°C, unless otherwise stated.
PARAMETER
SYMBOL
TEST CONDITIONS
IVDD
MIN
TYP
MAX
UNIT
Hi-Fi Record Mode,
CLK = 3.072MHz
980
1250
µA
Voice Mode,
CLK = 768kHz
300
400
Miscellaneous
Current Consumption
Sleep Mode,
CLK = 0Hz
Start-up time
Impulse recovery time
CLK frequency
from VDD applied to output
within specification
10
50
from CLK applied to output
within specification
10
50
from input sound pressure
below overload level to output
within specification
50
ms
ms
Hi-Fi Record Mode
2.4
6.144
MHz
Voice Mode
300
800
kHz
4
CLK
cycles
Sleep Mode
Mode selection time
10
0
Hz
TERMINOLOGY
1.
2.
3.
4.
5.
6.
7.
8.
Sensitivity (dBFS) – Sensitivity is a measure of the microphone output response to the acoustic pressure of a 1kHz 94dB SPL
(1Pa RMS) sine wave. This is referenced to the output Full Scale Range (FSR) of the microphone.
Full Scale Range (FSR) – Sensitivity, Electrical Noise Floor and Power Supply Rejection are measured with reference to the
output Full Scale Range (FSR) of the microphone. FSR is defined as the amplitude of a 1kHz sine wave output whose positive
peak value reaches 100% density of logic 1s and whose negative peak value reaches 0% density of logic 1s. This is the largest
1kHz sine wave that will fit in the digital output range without clipping. Note that, because the definition of FSR is based on a
sine wave, it is possible to support a square wave test signal output whose level is +3dBFS.
Total Harmonic Distortion (%) – 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.
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.
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.
All performance measurements are carried out within a 20Hz to 20kHz bandwidth 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 brick wall filter removes out of band noise.
Hi-Fi Record mode and Voice mode are selected according to CLK frequency, as described above.
Sleep Mode is enabled when the CLK input is stopped; this is a power-saving mode. Normal operation resumes automatically
when the CLK input frequency is within the specified operational limits. Note that the VDD supply is still required in Sleep
mode.
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AUDIO INTERFACE TIMING
tCY
CLK
(input)
DAT
(LRSEL = 1)
tL_DV
tL_DIS
tL_EN
tR_DV
DAT
(LRSEL = 0)
tR_DIS
tR_EN
DAT is high-impedance (hi-z) when not outputting data
Figure 1 Digital Microphone Interface Timing
Test Conditions
The following timing information is valid across the full range of recommended operating conditions.
PARAMETER
SYMBOL
MIN
TYP
MAX
UNIT
162
3333
ns
60:40
40:60
Digital Microphone Interface Timing
CLK cycle time
tCY
CLK duty cycle
CLK rise/fall time
DAT enable from rising CLK edge (LRSEL = 1)
6
tL_EN
14
DAT valid from rising CLK edge (LRSEL = 1)
tL_DV
20
DAT disable from falling CLK edge (LRSEL = 1)
tL_DIS
DAT enable from falling CLK edge (LRSEL = 0)
tR_EN
14
DAT valid from falling CLK edge (LRSEL = 0)
tR_DV
20
DAT disable from rising CLK edge (LRSEL = 0)
tR_DIS
ns
ns
90
ns
10
ns
ns
90
ns
10
ns
Notes:
1.
2.
3.
4.
The DAT output is high-impedance when not outputting data; this enables the outputs of two microphones to be connected
together with the data from one microphone interleaved with the data from the other. (The microphones must be configured to
transmit on opposite channels in this case.)
In a typical configuration, the Left channel is transmitted following the rising CLK edge (LRSEL = 1). In this case, the Left
channel should be sampled by the receiving device on the falling CLK edge.
Similarly, the Right channel is typically transmitted following the falling CLK edge (LRSEL = 0). In this case, the Right channel
should be sampled by the receiving device on the rising CLK edge.
The WM7236 operating mode is selected according to the CLK frequency; see “Acoustic and Electrical Characteristics” for
further details.
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TYPICAL PERFORMANCE
Sensitivity vs. Frequency
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THD vs. Sound Pressure Level
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APPLICATIONS INFORMATION
RECOMMENDED EXTERNAL COMPONENTS
It is recommended to connect a 0.1µF decoupling capacitor between the VDD and GND pins of the
WM7236. A ceramic 0.1µF capacitor with X7R dielectric or better is suitable. The capacitor should be
placed as close to the WM7236 as possible.
OPTIMISED SYSTEM RF DESIGN
For optimised RF design please refer to document WAN0278 (Recommended PCB Layout for
Microphone RF Immunity in Mobile Cell Phone Applications) for further information.
CONNECTION TO A WOLFSON AUDIO CODEC
Wolfson provides a range of audio CODECs incorporating a digital microphone input interface; these
support direct connection to digital microphones such as the WM7236.
Stereo connection of two WM7236 digital microphones is illustrated in Figure 2.
Further information on Wolfson audio CODECs is provided in the respective product datasheet, which
is available from the Wolfson website.
VDD
WM7236
VDD
Audio CODEC
CLK
0.1µF
DAT
LRSEL
DMICCLK
DMICDAT
GND
VDD
WM7236
VDD
CLK
0.1µF
DAT
LRSEL
GND
Figure 2 Stereo WM7236 Digital Microphone Connection
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PCB LAND PATTERN AND PASTE STENCIL
The recommended PCB Land Pattern and Paste Stencil Pattern for the WM7236 microphone are
shown in Figure 3 and Figure 4.
See also Application Note WAN0284 (General Design Considerations for MEMS Microphones) for
further details of PCB footprint design.
Full definition of the package dimensions is provided in the “Package Dimensions” section.
Figure 3 DM116 - PCB Land Pattern, Top View
Figure 4 DM116 - Paste Stencil Pattern, Top View
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WM7236, WM7236E
PACKAGE DIMENSIONS
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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 :: sales@wolfsonmicro.com
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WM7236, WM7236E
REVISION HISTORY
DATE
REV
12/03/14
1.0
Initial Release
DESCRIPTION OF CHANGES
23/04/14
1.1
PCB Land Pattern and Paste Stencil drawings updated/added
9
PH
28/05/14
2.0
Electrical Noise Floor (Voice Mode) figure updated
5
PH
30/09/14
2.1
Operating frequency range extended
Electrical Characteristics updated
Performance graphs added
4, 7
1, 5, 6
8
PH
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CHANGED BY
MUmM
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