Application information

TS472

16/25

Doc ID 11015 Rev 6

Figure 37 gives other values of the gain vs. voltage applied on the GS pin.

Figure 37.

Gain vs. gain select voltage

Note:

In the case of a single-ended output configuration (either positive or negative output is used

for the following signal processing) the overall gain is half. One must also take into account

that all advantages of the differential configuration principles are lost (see the difference in

PSRR in Table 5).

4.6

Wake-up time

When the standby mode is released to switch the device to ON, a signal appears on the

output a few microseconds later, and the bypass capacitor Cb is charged within a few

milliseconds. As Cb is directly linked to the bias of the amplifier, the bias will not work

properly until the Cb voltage is correct.

In a typical application, when a biased microphone is connected to the differential input via

the input capacitors (Cin), (and the output signal is in line with the specification), the wake-up

time will depend upon the values of the input capacitors Cin and the gain. When the gain is

lower than 0 dB, the wake-up time is determined only by the bypass capacitor Cb, as

described above. For a gain superior to 0 dB, refer to Figure 38.

Figure 38.

Wake-up time in a typical application vs. input capacitors

0

0.2

0.4

0.6

0.8

4

5

-80

-60

-40

-20

0

20

40

Tamb=25

°C

V

GS

(V)

20

40

60

80

100

0

10

20

30

40

50

60

Gain=20dB

Tamb = 25°C

Vcc=3V

Cb=1

μF

Input capacitors C

IN

(nF)

Maximum Gain