Preliminary Technical Data

WM7230

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PTD, Rev 2.4, October 2012

5

ACOUSTIC AND ELECTRICAL CHARACTERISTICS

Test Conditions:

PARAMETER

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Directivity

Omni-directional

Sensitivity (WM7230)

S

94 dB SPL

-29

-26

-23

dBFS

Sensitivity (WM7230E)

S

94 dB SPL

-27

-26

-25

dBFS

Acoustic Overload

THD < 10%

120

dB SPL

Signal to Noise Ratio

SNR

A-Weighted

61

dB

Total Harmonic Distortion

THD

100dB SPL

0.1

1

%

Dynamic Range

DR

A-weighted noise floor to 1%

THD

85

dB

Frequency Response

+3dB High frequency

17000

Hz

Acoustic Noise Floor

A-weighted

33

dB SPL

Electrical Noise Floor

A-weighted

-87

dBFS

Power Supply Rejection

PSR

217Hz Square Wave

100mV pk-pk

-70

dBFS

Digital Input / Output

CLK Input HIGH Level

0.65 x

VDD

V

CLK Input LOW Level

0.35 x

VDD

V

DAT Output HIGH Level

0.9 x

VDD

V

DAT Output LOW Level

0.1 x

VDD

V

Input capacitance (CLK)

0.5

pF

Maximum load capacitance

(DAT)

100

pF

Input Leakage

1

μA

Short Circuit Output Current

DAT connected to GND

10

mA

Miscellaneous

Current Consumption

Active Mode

700

μA

SLEEP Mode

2

10

Start-up Time

From OFF

10

ms

From SLEEP

10

CLK Sleep Frequency

1.0

kHz

TERMINOLOGY

1.

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.

2.

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 undistorted 1kHz sine wave that will fit in the digital output numerical range. 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.

3.

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.

4.

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.

5.

All performance measurements are carried out with 20kHz 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 brick wall filter removes out of band noise.