Pre-Production

WM7231

w

PP, Rev 3.0, January 2014

5

ACOUSTIC AND ELECTRICAL CHARACTERISTICS

Test Conditions:

PARAMETER

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Directivity

Omni-directional

Polarity (see note)

Positive sound pressure

Decreasing density of 1’s

Sensitivity (WM7231)

S

94 dB SPL

-29

-26

-23

dBFS

Sensitivity (WM7231E)

S

94 dB SPL

-27

-26

-25

dBFS

Acoustic Overload

THD < 10%

120

dB SPL

Signal to Noise Ratio

SNR

A-Weighted

60

dB

Total Harmonic Distortion

THD

100dB SPL

0.1

1

%

Dynamic Range

DR

A-Weighted,

Noise floor to 1% THD

84

dB

Frequency Response

-3dB High frequency

85

Hz

+3dB High frequency

17000

Hz

Acoustic Noise Floor

A-weighted

34

dB SPL

Electrical Noise Floor

A-weighted

-86

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)

200

pF

Input Leakage

1

μA

Short Circuit Output Current

DAT connected to GND

10

mA

Miscellaneous

Current Consumption

Active Mode

735

μA

SLEEP Mode

2

10

Start-up Time

From OFF

10

ms

From SLEEP

10

CLK Sleep Frequency

1.0

kHz

Note:

The WM7231 generates a single-bit digital (PDM) output in response to the acoustic input. A positive sound pressure

on the diaphragm generates a decreasing density of 1’s in the PDM stream (ie. there is a phase inversion between the

acoustic input and the digital output).