MICROPHONE, -38DB, OMNI

SPM0204LE5-QB

Manufacturer Part NumberSPM0204LE5-QB
DescriptionMICROPHONE, -38DB, OMNI
ManufacturerKnowles Acoustics
SPM0204LE5-QB datasheet
 


Specifications of SPM0204LE5-QB

Transducer FunctionMicrophoneDevice TypeMicrophone
DirectivityOmniSensitivity-38
Supply Voltage Min1.5VDrain Current Max0.25mA
Supply Voltage3.6VSupply Voltage Max3.6V
Filter TypeRFILead Free Status / RoHS StatusLead free / RoHS Compliant
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MICROPHONE AND SPEAKER BASICS
MICROPHONE AND SPEAKER BASICS
MICROPHONES
Microphones measure sound pressure. Inside a Knowles microphone is a thin flexible diaphragm, an electrically
charged plate, and an amplifier (Fig. 1). The output voltage is proportional to changes in the small separation
between the diaphragm and the charged plate (Fig. 2).
As sound pressure inside the front cavity increases, the diaphragm is pushed closer to the plate. As the
pressure decreases, it moves further away. The motion of the diaphragm produces a small electrical signal that
is amplified by a miniature circuit inside the microphone.
The sensitivity of a typical Knowles’ microphone is measured in units of dB relative to 1 Volt per 0.1 Pascal.
Fig 1: Cross section of a Knowles EM microphone
OUTPUT TERMINAL
AMPLIFIER
CHARGE PLATE
FIG. 2: EM diaphragm and electret
CHARGE PLATE
26
DIAPHRAGM
FRONT CAVITY
DIAPHRAGM
AIR GAP SEPARATION
www.knowles.com
WIRE
SOUND PRESSURE