WM7120A Datasheet, PDF (5/12 Pages) Wolfson Microelectronics plc – Top Port Analogue Silicon Microphone

Pre-Production
ACOUSTIC AND ELECTRICAL CHARACTERISTICS
WM7120A
Test Conditions: VDD=2.1V, 1kHz test signal, TA = 25°C
PARAMETER
Directivity
Sensitivity (WM7120A)
Sensitivity (WM7120AE)
Acoustic Overload
SYMBOL
S
S
Signal to Noise Ratio
Total Harmonic Distortion
Dynamic Range
SNR
THD
DR
Frequency Response
Acoustic Noise Floor
Electrical Noise Floor
Power Supply Rejection Ratio
Current Consumption
Output DC Impedance
PSRR
I_VDD
ZOUT
TEST CONDITIONS
94dB SPL
94dB SPL
No Load
THD < 10%
A-Weighted
104dB SPL
A-Weighted,
Noise floor to 1% THD
-3dB Low Frequency
+3dB High Frequency
A-Weighted
A-Weighted
100mV RMS, 217Hz
MIN
TYP
MAX
Omni-directional
-45
-42
-39
-43
-42
-41
131
57
0.25
88
62
9300
37
-99
50
140
190
100
UNIT
dBV
dBV
dB SPL
dB
%
dB
Hz
Hz
dB SPL
dBV
dB
µA
Ω
TERMINOLOGY
1. Sensitivity (dBV) - Sensitivity is a measure of the microphone output response to the acoustic pressure of a 1kHz
94dB SPL (1Pa RMS) sine wave.
2. 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.
3. Total Harmonic Distortion (dB) – 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.
4. Dynamic Range (dB) – DR is the ratio of the 1% THD microphone output level (in response to a sine wave input) and
the idle noise output level.
5. All performance measurements are carried out with 20 kHz 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 low pass filter removes out of band noise.
w
PP, Rev 3.1, April 2012
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