TS472_06 datasheet(16/24 Pages) STMICROELECTRONICS

16 / 24 page

Application information

TS472

16/24

5.5

Gain settings

The gain in the application depends mainly on:

●

the sensitivity of the microphone

●

the distance to the microphone

●

the audio level of the sound

●

the desired output level

The sensitivity of the microphone is generally expressed in dB/Pa, referenced to 1V/Pa. For

example, the microphone used in testing had an output voltage of 6.3mV for a sound

pressure of 1 Pa (where Pa is the pressure unit, Pascal). Expressed in dB, the sensitivity is:

20Log(0.0063) = -44 dB/Pa

To facilitate the first approach, Table 11 below gives voltages and gains used with a low cost

omnidirectional electret condenser microphone of -44dB/Pa.

The gain of the TS472 microphone preamplifier can be set:

From -1.5 dB to 41 dB by connecting an external grounded resistor RGS to the GS pin.

It allows to adapt more precisely the gain to each application.

To 20dB by applying VGS > 1VDC on Gain Select (GS) pin. This setting can help to

reduce a number of external components in an application, because 2.0 VDC is

provided by TS472 itself on BIAS pin.

Table 11.

Typical TS472 gain vs. distance to the microphone (sensitivity -44dB/Pa)

Distance to microphone

Microphone output voltage

TS472 Gain

1cm

30mVRMS

20cm

3mVRMS

100

Table 12.

Selected gain vs. gain select resistor

Gain (dB)

010

RGS (Ω)

470k

27k

4k7

Figure 35. Gain in dB vs. gain select resistor

Figure 36. Gain in V/V vs. gain select resistor

100

10k

100k

-10

Tamb=25

°C

(

Ω)

100

10k

100k

100

Tamb=25

°C

(

Ω)

TS472 数据表(PDF) 16 Page - STMicroelectronics

TS472 数据表(HTML) 16 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

数据表下载