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WM7231, WM7231E

Bottom Port Digital Silicon Microphone

WOLFSON MICROELECTRONICS plc

Pre-Production, January 2014, Rev 3.0

Copyright

2014 Wolfson Microelectronics plc

DESCRIPTION

The WM7231 is a low-profile silicon digital microphone. It

offers high Signal to Noise Ratio (SNR) and low power

consumption and is suited to a wide variety of consumer

applications.

The

WM7231

incorporates

Wolfson’s

proprietary

CMOS/MEMS

membrane

technology,

offering

high

reliability and high performance in a miniature, low-profile

package. The WM7231 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 WM7231 incorporates a high performance ADC,

which outputs a single-bit Pulse Density Modulated (PDM)

audio data stream. The WM7231 supports selectable

left/right channel assignment for a two-channel digital

microphone interface, enabling efficient connection of

multiple microphones in stereo/array configurations.

The WM7231E 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.

FEATURES



High SNR; selectable sensitivity tolerance options

-

WM7231 – SNR 60dB, Sensitivity +/-3dB

-

WM7231E – SNR 60dB, Sensitivity +/-1dB



Low power

-

Sleep Mode - 2μA

-

Normal Operation - 735μA



Low profile packaging



Support for automated flow solder assembly



PDM Digital audio output



Stereo/array operation



Proprietary ADC technology

-

Reduced clock jitter sensitivity

-

Low noise floor modulation

-

Stable in overload condition



Bottom Port Package



1.62V to 3.7V supply



4.00 mm x 3.00 mm x 1.00mm Thin Package Design

APPLICATIONS



Mobile telephone handsets



Portable computers



Portable media players



Digital still cameras



Digital video cameras



Bluetooth headsets



Portable navigation devices

BLOCK DIAGRAM

WM7231

AMP

Transducer

(CMOS MEMS)

VDD

DAT

CHARGE

PUMP

GND

ADC

CONTROL

CLK

LRSEL