Datasheet

ManualsBrandsADAFRUIT ManualsDev KitsPCB extension board

AVAILABLE

EVALUATION KIT AVAILABLE

Functional Diagrams

Pin Configurations appear at end of data sheet.

Functional Diagrams continued at end of data sheet.

UCSP is a trademark of Maxim Integrated Products, Inc.

For pricing, delivery, and

ordering information, please contact Maxim Direct

at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.

General Description

The MAX9814 is a low-cost, high-quality microphone

amplifier with automatic gain control (AGC) and low-

noise microphone bias. The device features a low-noise

preamplifier, variable gain amplifier (VGA), output

amplifier, microphone-bias-voltage generator and AGC

control circuitry.

The low-noise preamplifier has a fixed 12dB gain, while

the VGA gain automatically adjusts from 20dB to 0dB,

depending on the output voltage and the AGC thresh-

old. The output amplifier offers selectable gains of 8dB,

18dB, and 28dB. With no compression, the cascade of

the amplifiers results in an overall gain of 40dB, 50dB,

or 60dB. A trilevel digital input programs the output

amplifier gain. An external resistive divider controls the

AGC threshold and a single capacitor programs the

attack/release times. A trilevel digital input programs

the ratio of attack-to-release time. The hold time of the

AGC is fixed at 30ms. The low-noise microphone-bias-

voltage generator can bias most electret microphones.

The MAX9814 is available in the space-saving, 14-pin

TDFN package. This device is specified over the

-40°C to +85°C extended temperature range.

Applications

Features

♦ Automatic Gain Control (AGC)

♦ Three Gain Settings (40dB, 50dB, 60dB)

♦ Programmable Attack Time

♦ Programmable Attack and Release Ratio

♦ 2.7V to 5.5V Supply Voltage Range

♦ Low Input-Referred Noise Density of 30nV/√Hz

♦ Low THD: 0.04% (typ)

♦ Low-Power Shutdown Mode

♦ Internal Low-Noise Microphone Bias, 2V

♦ Available in the Space-Saving, 14-Pin TDFN (3mm

x 3mm) Package

♦ -40°C to +85°C Extended Temperature Range

Microphone Amplifier with AGC and

Low-Noise Microphone Bias

Ordering Information

Simplified Block Diagram

LOW-NOISE

REFERENCE

AGC

2.7V TO 5.5V

LNA

+12dB

VGA

+20dB/0dB

GAIN

+8/+18/

+28dB

MICBIAS

MICIN

MICOUT

OUT

GND

SHDN

MAX9814

PART TEMP RANGE PIN-PACKAGE

MAX9814ETD+T -40°C to +85°C 14 TDFN-EP*

Denotes a lead(Pb)-free/RoHS-compliant package.

T = Tape and reel.

EP = Exposed pad.

Pin Configurations appear at end of data sheet.

Digital Still Cameras

Digital Video Cameras

PDAs

Bluetooth Headsets

Entertainment Systems

(e.g., Karaoke)

Two-Way Communicators

High-Quality Portable

Recorders

IP Phones/Telephone

Conferencing

MAX9814

19-0764; Rev 2; 6/09

Summary of content (30 pages)

PAGE 1
EVALUATION KIT AVAILABLE MAX9814 LE AVAILAB Microphone Amplifier with AGC and Low-Noise Microphone Bias General Description The MAX9814 is a low-cost, high-quality microphone amplifier with automatic gain control (AGC) and lownoise microphone bias. The device features a low-noise preamplifier, variable gain amplifier (VGA), output amplifier, microphone-bias-voltage generator and AGC control circuitry.
PAGE 2
MAX9814 Microphone Amplifier with AGC and Low-Noise Microphone Bias ABSOLUTE MAXIMUM RATINGS VDD to GND ..............................................................-0.3V to +6V All Other Pins to GND.................................-0.3V to (VDD + 0.3V) Output Short-Circuit Duration.....................................Continuous Continuous Current (MICOUT, MICBIAS).......................±100mA All Other Pins ....................................................................
PAGE 3
MAX9814 Microphone Amplifier with AGC and Low-Noise Microphone Bias ELECTRICAL CHARACTERISTICS (continued) (VDD = 3.3V, SHDN = VDD, CCT = 470nF, CCG = 2µF, GAIN = VDD, TA = TMIN to TMAX, unless otherwise specified. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MICOUT High Output Voltage VOH IOUT sourcing 1mA MICOUT Low Output Voltage VOL IOUT sinking 1mA MICOUT Bias MICOUT unconnected MIN 1.14 TYP MAX UNITS 2.45 V 3 mV 1.23 1.
PAGE 4
MAX9814 Microphone Amplifier with AGC and Low-Noise Microphone Bias Typical Operating Characteristics (VDD = 5V, CCT = 470nF, CCG = 2.2µF, VTH = VMICBIAS x 0.4, GAIN = VDD (40dB), AGC disabled, no load, RL = 10kΩ, COUT = 1µF, TA = +25°C, unless otherwise noted.) -10 -40 -20 -50 50 -30 -60 GAIN = 0 30 PSRR (dB) 60 40 -40 MAX9814 toc03 -30 MAX9814 toc02 GAIN = UNCONNECTED PSRR (dB) GAIN (dB) 0 MAX9814 toc01 80 70 MICBIAS POWER-SUPPLY REJECTION RATIO vs.
PAGE 5
MAX9814 Microphone Amplifier with AGC and Low-Noise Microphone Bias Typical Operating Characteristics (continued) (VDD = 5V, CCT = 470nF, CCG = 2.2µF, VTH = VMICBIAS x 0.4, GAIN = VDD (40dB), AGC disabled, no load, RL = 10kΩ, COUT = 1µF, TA = +25°C, unless otherwise noted.) VMICIN 10mV/div 0V 1000 MAX9814 toc12 MAX9814 toc11 MAX9814 toc10 MICBIAS NOISE (nVRMS/√Hz) TURN-ON RESPONSE SMALL-SIGNAL PULSE RESPONSE MICBIAS NOISE vs.
PAGE 6
MAX9814 Microphone Amplifier with AGC and Low-Noise Microphone Bias Typical Operating Characteristics (continued) (VDD = 5V, CCT = 470nF, CCG = 2.2µF, VTH = VMICBIAS x 0.4, GAIN = VDD (40dB), AGC disabled, no load, RL = 10kΩ, COUT = 1µF, TA = +25°C, unless otherwise noted.
PAGE 7
MAX9814 Microphone Amplifier with AGC and Low-Noise Microphone Bias Detailed Description The MAX9814 is a low-cost, high-quality microphone amplifier with automatic gain control (AGC) and a lownoise microphone bias. The MAX9814 consists of several distinct circuits: a low-noise preamplifier, a variable gain amplifier (VGA), an output amplifier, a microphonebias-voltage generator, and AGC control circuitry.
PAGE 8
MAX9814 Microphone Amplifier with AGC and Low-Noise Microphone Bias and setting the attack-to-release time ratio by configuring A/R as shown in Table 1: HOLD VCT 500mV/div ATTACK • Use a small ratio to maximize the speed of the AGC. • Use a large ratio to maximize the sound quality and prevent repeated excursions above the threshold from being independently adjusted by the AGC.
PAGE 9
MAX9814 Microphone Amplifier with AGC and Low-Noise Microphone Bias Setting the AGC Threshold To set the output-voltage threshold at which the microphone output is clamped, an external resistor-divider must be connected from MICBIAS to ground with the output of the resistor-divider applied to TH. The voltage VTH determines the peak output-voltage threshold at which the output becomes clamped.
PAGE 10
MAX9814 Microphone Amplifier with AGC and Low-Noise Microphone Bias Typical Application Circuit/Functional Diagram VDD CBYPASS 1μF SHDN VDD MICBIAS MAX9814 BIAS A/R CBIAS 0.47μF R1 150kΩ TH VDD MICBIAS REF AGC GAIN R2 100kΩ RMICBIAS 2.21kΩ MICIN LNA VGA CIN 0.1μF MICOUT COUT ROUT CT CCT 470nF CG CCG 2.2μF GND *THE DEVICE HAS BEEN CONFIGURED WITH AN ATTACK TIME OF 1.1ms, 40dB GAIN, AND AN ATTACK-AND-RELEASE RATIO OF 1:500.
PAGE 11
MAX9814 Microphone Amplifier with AGC and Low-Noise Microphone Bias Pin Configuration Chip Information PROCESS: BiCMOS TH MICBIAS BIAS N.C. GAIN A/R MICIN TOP VIEW 14 13 12 11 10 9 8 MAX9814 5 6 7 GND CG 4 MICOUT 3 VDD 2 N.C.
PAGE 12
MAX9814 Microphone Amplifier with AGC and Low-Noise Microphone Bias Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. 12 PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
PAGE 13
MAX9814 Microphone Amplifier with AGC and Low-Noise Microphone Bias Package Information (continued) For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. COMMON DIMENSIONS PACKAGE VARIATIONS MIN. MAX. PKG. CODE N D2 E2 e JEDEC SPEC b A 0.70 0.80 T633-2 6 1.50±0.10 2.30±0.10 0.95 BSC MO229 / WEEA 0.40±0.05 1.90 REF D 2.90 3.10 T833-2 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF SYMBOL [(N/2)-1] x e E 2.90 3.
PAGE 14
MAX9814 Microphone Amplifier with AGC and Low-Noise Microphone Bias Revision History REVISION NUMBER REVISION DATE 0 3/07 Initial release 1 2/09 Updated Ordering Information, Absolute Maximum Ratings, Pin Description, and Pin Configuration sections to include EP for TDFN package 2 6/09 Removed UCSP package DESCRIPTION PAGES CHANGED — 1, 2, 6, 11 1, 2, 6, 11, 12 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product.
PAGE 15
PART NUMBER: CMA-4544PF-W page 1 of 4 date 06/2008 DESCRIPTION: electret condenser microphone SPECIFICATIONS directivity sensitivity (S) sensitivity reduction (ΔS-Vs) operating voltage output impedance (Zout) operating frequency (f) current consumption (IDSS) signal to noise ratio (S/N) operating temperature storage temperature dimensions weight material terminal RoHS omnidirectional -44 ±2 dB f = 1KHz, 1Pa -3 dB f = 1KHz, 1Pa 3 V dc (standard), 10 V dc (max.) 2.2 KΩ f = 1KHz, 1Pa 20 ~ 20,000 Hz 0.
PAGE 16
PART NUMBER: CMA-4544PF-W page 2 of 4 date 06/2008 DESCRIPTION: electret condenser microphone MEASUREMENT CIRCUIT FREQUENCY RESPONSE CURVE 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.
PAGE 17
page 3 of 4 date 06/2008 DESCRIPTION: electret condenser microphone PART NUMBER: CMA-4544PF-W MECHANICAL CHARACTERISTICS item soldering heat resistance PCB wire pull strength vibration drop test test condition evaluation standard Lead terminals are immersed in solder bath of No interference in operation. 270 ±5°C for 2 ±0.5 seconds. The pull force will be applied to double lead wire: No damage or cutting off. Horizontal 4.9N (0.
PAGE 18
PART NUMBER: CMA-4544PF-W page 4 of 4 date 06/2008 DESCRIPTION: electret condenser microphone PACKAGING 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.
PAGE 19
Adafruit AGC Electret Microphone Amplifier - MAX9814 Created by lady ada Last updated on 2015-06-22 11:30:12 AM EDT
PAGE 20
Guide Contents Guide Contents Overview Assembly Prepare the header strip: Add the breakout board: And Solder! Wiring and Test Wiring Test! Do more! Downloads Datasheets 3D models Schematics © Adafruit Industries https://learn.adafruit.
PAGE 21
Overview This fancy microphone amplifier module is a step above the rest, with built in automatic gain control. The AGC in the amplifier means that nearby 'loud' sounds will be quieted so they don't overwhelm & 'clip' the amplifier, and even quiet, far-away sounds will be amplified. This amplifier is great for when you want to record or detect audio in a setting where levels change and you don't want to have to tweak the amplifier gain all the time.
PAGE 22
Specifications: Supply Voltage: 2.7v-5.5v @ 3mA current Output: 2Vpp on 1.25V bias Frequency Response: 20Hz - 20 KHz Programmable Attack and Release Ratio Automatic gain, selectable max from 40dB, 50dB or 60dB Low Input-Referred Noise Density of 30nV/ Low THD: 0.04% (typ) © Adafruit Industries https://learn.adafruit.
PAGE 23
Assembly Assembly is really easy, you can use straight or 'right-angle' style headers to attach to the PCB. We'll be using the plain straight headers included The board comes with all surface-mount components pre-soldered. The included header strip can be soldered on for convenient use on a breadboard or with 0.1" connectors. You can also skip this step and solder on wires. Prepare the header strip: Cut the strip to length if necessary.
PAGE 24
Add the breakout board: Place the breakout board over the pins so that the short pins poke through the breakout pads And Solder! Be sure to solder all 5 pins for reliable electrical contact. (For tips on soldering, be sure to check out our Guide to Excellent Soldering (http://adafru.it/aTk)). © Adafruit Industries https://learn.adafruit.
PAGE 26
Wiring and Test The microphone amp is thankfully quite simple to get started. No microcontroller or programming required. We suggest wiring it up directly with a battery pack and headphones to start while you get a hang of how the AGC acts and responds. You'll need a 3 or 4 AA/AAA battery pack (http://adafru.it/727)(or some external source of 3-5VDC) - we suggest batteries since they are very electrically-quiet compared to USB or wall power adapters.
PAGE 27
Wiring Connect the amplifier, battery pack and headphone jack as shown above. For the Microphone amp: GND connects to the battery pack ground - black wire VDD connects to the battery pack positive - red wire Connect the Gain pin to VDD for now - green wire Connect the OUT pin to a 1uF-100uF capacitor (really any value will do).
PAGE 28
Now try listening to sounds on the headphones, you should notice a strange 'effect' where you can hear people from further away than your hearing is used to! Try setting the Gain pin to the GND pin to get 10dB more gain. You can also remove the Gain wire, to set the gain to 60dB but you may find the gain is way too high, and it sounds 'too noisy', so we suggest sticking to 40 or 50dB for most purposes.
PAGE 29
Downloads Datasheets Datasheet for the MAX9814 (http://adafru.it/d9o) Datasheet for the electret mic capsule (http://adafru.it/aW6) 3D models Thanks to Aron Rubin! adafruit_mic_agc.pdf http://adafru.it/frD adafruit_mic_agc.skp http://adafru.it/frE Schematics PCB Dimensional Diagram © Adafruit Industries https://learn.adafruit.