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Preliminary Technical Data
FEATURES
Small and thin 3 mm x 4 mm x 1 mm surface-mount package High SNR of 60.5 dBA High sensitivity of -26 dBFS Flat frequency response from 100 Hz to over 12 kHz Low current consumption: <650 A High PSRR of 80 dBFS Fourth-order - modulator Digital PDM output Compatible with Sn/Pb and Pb-free solder processes RoHS/WEEE compliant
Omnidirectional Microphone with Bottom Port and Digital Output ADMP421
GENERAL DESCRIPTION
The ADMP421 is a low cost, low power, digital output bottom ported omnidirectional MEMS microphone. The ADMP421 consists of a MEMS microphone element, an output amplifier, and a fourth-order - modulator. The digital interface allows for the pulse density modulated (PDM) output of two microphones to be time multiplexed on a single data line using a single clock. The ADMP421 has a high SNR and a high sensitivity, making it an excellent choice for far field applications. The ADMP421 has a flat wideband frequency response resulting in natural sound with high intelligibility. Low current consumption enables long battery life for portable applications. A built-in particle filter provides for high reliability. The ADMP421 is available in a thin 3 mm x 4 mm x 1 mm surface-mount package. It is reflow solder compatible with no sensitivity degradation.
APPLICATIONS
Cell phones PC audio Digital cameras Bluetooth headsets
FUNCTIONAL BLOCK DIAGRAM
HIGH-PASS FILTER FOURTH-ORDER - CONVERTER OUTPUT DRIVER
BUFFER MEMS SIGNAL
DATA
REFERENCE VOLTAGE BIAS CURRENT MEMBRANE BACKPLATE LOW POWER DETECTOR MEMS VBIAS
ADC TIMING GENERATOR
L/R CLK CHARGE PUMP
07596-001
VDD FILTER GND
Figure 1.
Rev. PrA
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 (c)2008 Analog Devices, Inc. All rights reserved.
ADMP421 TABLE OF CONTENTS
Features .............................................................................................. 1 Applications ....................................................................................... 1 General Description ......................................................................... 1 Functional Block Diagram .............................................................. 1 Specifications..................................................................................... 3 Timing Characteristics ................................................................ 4 Timing Diagram ........................................................................... 4 Absolute Maximum Ratings............................................................ 5 ESD Caution .................................................................................. 5
Preliminary Technical Data
Typical Performance Characteristics ..............................................6 Pin Configuration and Function Descriptions..............................7 Handling Instructions .......................................................................8 Pick and Place Equipment............................................................8 Reflow Solder .................................................................................8 Board Wash ....................................................................................8 Outline Dimensions ..........................................................................9 Ordering Guide .............................................................................9
Rev. PrA | Page 2 of 12
Preliminary Technical Data SPECIFICATIONS
ADMP421
TA = 25C, VDD = 1.8 V, CLK = 2.4 MHz, unless otherwise noted. All minimum and maximum specifications are guaranteed. Typical specifications are not guaranteed. Table 1.
Parameter PERFORMANCE Directionality Sensitivity 1 Signal-to-Noise Ratio Equivalent Input Noise Frequency Response Total Harmonic Distortion Power Supply Rejection Ratio Maximum Acoustic Input INPUT CHARACTERISTICS Clock Supply Voltage Symbol Conditions Min Typ Omni -26 60.5 33.5 0 0 80 120 1 1.65 2.25 3.0 Normal mode Sleep mode VDD 0 Noninverting 2 3.25 2.0 2.75 3.6 650 50 Max Unit
1 kHz, 94 dB SPL SNR EIN 100 Hz to 10 kHz 100 Hz to 12 kHz 105 dB SPL 217 Hz, 100 mV p-p square wave superimposed on VDD = 1.8 V Peak
-29 59 -2 -3 70
-23
THD PSRR
+2 +2 3
dBFS dBA dBA SPL dB dB % dBFS dB SPL MHz V V V A A V V
CLK VDD
1.8 2.5 3.3
Supply Current OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Polarity
1 2
IS
VOH VOL
Relative to the rms level of a sine wave with positive amplitude equal to 100% 1s density, and negative amplitude equal to 0% 1s density. Positive going (increasing) pressure on the membrane results in an increase in the number of 1s at the output.
Rev. PrA | Page 3 of 12
ADMP421
TIMING CHARACTERISTICS
Table 2.
Parameter Input tCLKIN Output t1OUTEN t1OUTDIS t2OUTEN t2OUTDIS Description Input Clock Period DATA1 driven after falling clock edge DATA1 disable after rising clock edge DATA2 driven after rising clock edge DATA2 disable after falling clock edge
Preliminary Technical Data
Min 310 30
Max 1000
Unit ns ns ns ns ns
20 30 20
TIMING DIAGRAM
tCLKIN
CLK
t1OUTEN
DATA1
t1OUTDIS
t2OUTDIS
07596-005
DATA2
t2OUTEN
Figure 2. Pulse Density-Modulated Output Timing
Rev. PrA | Page 4 of 12
Preliminary Technical Data ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter Supply Voltage Sound Pressure Level (SPL) Mechanical Shock Vibration Temperature Range Rating 3.6 V 160 dB 20,000 g Per Military 883E specification -40C to +85C
ADMP421
Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ESD CAUTION
TP RAMP-UP TL
tP
CRITICAL ZONE TL TO TP
TEMPERATURE
TSMAX TSMIN
tL
t25C TO PEAK
TIME
Figure 3. Recommended Soldering Profile
Table 3. Recommended Soldering Profile
Profile Feature Average Ramp Rate (TL to TP) Preheat Minimum Temperature (TSMIN) Maximum Temperature (TSMAX) Time (TSMIN to TSMAX), tS TSMAX to TL Ramp-Up Rate Time Maintained Above Liquidous (tL) Liquidous Temperature (TL) Peak Temperature (TP) Time within 5C of Actual Peak Temperature (tP) Ramp-Down Rate Time 25C to Peak Temperature Sn63/Pb37 3C/sec max 100C 150C 60 sec to 120 sec 3C/sec 60 sec to 150 sec 183C 240C + 0C/-5C 10 sec to 30 sec 6C/sec max 6 minute max Pb-Free 3C/sec max 150C 200C 60 sec to 120 sec 3C/sec 60 sec to 150 sec 217C 260C + 0C/-5C 20 sec to 40 sec 6C/sec max 8 minute max
Rev. PrA | Page 5 of 12
07596-002
PREHEAT
tS
RAMP-DOWN
ADMP421 TYPICAL PERFORMANCE CHARACTERISTICS
10 8 6 4 SENSITIVITY (dB) 2 0 -2 -4 -6 -8
07596-003
Preliminary Technical Data
-40
-50
-60
PSRR (dBFS)
-70
-80
-90
100
1k FREQUENCY (Hz)
10k
500
1k
2k
5k
10k
20k
FREQUENCY (Hz)
Figure 4. Typical Frequency Response
Figure 5. Typical Power Supply Rejection Ratio vs. Frequency
Rev. PrA | Page 6 of 12
07596-004
-10
-100 200
Preliminary Technical Data PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
DATA 5 VDD 4
1 CLK 2 L/R SELECT 3 GND
07596-006
ADMP421
Figure 6. Pin Configuration (Bottom View)
Table 6. Pin Function Descriptions
Pin No. 1 2 Mnemonic CLK L/R SELECT Description Clock Input to Microphone. Left Channel or Right Channel Select. DATA1: L/R SELECT tied to GND. DATA2: L/R SELECT pulled to VDD. Ground. Power Supply. Digital Output Signal (DATA1, DATA2).
3 4 5
GND VDD DATA
Rev. PrA | Page 7 of 12
ADMP421 HANDLING INSTRUCTIONS
PICK AND PLACE EQUIPMENT
The MEMS microphone can be handled using standard pickand-place and chip shooting equipment. Care should be taken 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. Use care during pick-and-place to ensure no high shock events above 20 kg are experienced because this may cause damage to the microphone. 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 or blow air into the microphone port. Do not use excessive force to place the microphone on the PCB.
Preliminary Technical Data
REFLOW SOLDER
Standard reflow solder conditions specified in Figure 3 can be used to attach the MEMS microphone to the PCB.
BOARD WASH
When washing the PCB, ensure that water does not make contact with the microphone port. Blow-off procedures and ultrasonic cleaning must not be used.
*
*
*
Rev. PrA | Page 8 of 12
Preliminary Technical Data OUTLINE DIMENSIONS
REFERENCE CORNER
ADMP421
0.95 0.35 0.10
0.40 x 0.60 (Pins 1-4)
4.05 4.00 3.95
2.05 0.70
REFERENCE CORNER
R 0.10 (2 x)
1 2 3
3.05 3.00 2.95 0.12 TOP VIEW 1.10 1.00 0.90 SIDE VIEW 0.82 0.76 0.70
0.90
0.50 DIA. (THRU HOLE)
0.45
5
4
1.05 BOTTOM VIEW 0.30
1.10 DIA. 1.70 DIA.
Figure 7. 5-Terminal Chip Array Small Outline No Lead Cavity [LGA_CAV] 4 mm x 3 mm Body (CE-5-1) Dimensions shown in millimeters
2.05 2.00 1.95
2
8.00 1.60 MAX 1.50 NOM A 0.35 0.30 0.25 0.20 MAX
4.00
1
1.85 1.75 1.65
12.30 12.00 11.70
3.40 4.16 1.50 MIN DIA
5.55 5.50 5.45
2
DETAIL A
A
0.25
1.30 SECTION A-A
0.50 R DETAIL A
Figure 8. LGA_CAV Tape and Reel Outline Dimensions Dimensions shown in millimeters
ORDERING GUIDE
Model ADMP421ACEZ-RL 1 ADMP421ACEZ-RL71
1
Temperature Range -40C to +85C -40C to +85C
Package Description 5-Terminal LGA_CAV, 13" Tape and Reel 5-Terminal LGA_CAV, 7" Tape and Reel
Package Option CE-5-1 CE-5-1
Ordering Quantity 4,000 1,000
Z = RoHS Compliant Part.
Rev. PrA | Page 9 of 12
062408-A
NOTES: 1. 10 SPROCKET HOLE PITCH CUMULATIVE TOLERANCE 0.20. 2. POCKET POSITION RELATIVE TO SPROCKET HOLE MEASURED AS TRUE POSITION OF POCKET, NOT POCKET HOLE.
0.25
062508-C
0.24 NOM
ADMP421 NOTES
Preliminary Technical Data
Rev. PrA | Page 10 of 12
Preliminary Technical Data NOTES
ADMP421
Rev. PrA | Page 11 of 12
ADMP421 NOTES
Preliminary Technical Data
(c)2008 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. PR07596-0-9/08(PrA)
Rev. PrA | Page 12 of 12

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