TDA1910(1997) データシートの表示（PDF） - STMicroelectronics

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TDA1910
(Rev.:1997)

10W AUDIO AMPLIFIER WITH MUTING

STMicroelectronics 

TDA1910

MUTING FUNCTION

The output signal can be inhibited applying a DC voltage VT to pin 11, as shown in fig. 28

Figure 28

The input resistance at pin 1 depends on the threshold voltage VT at pin 11 and is typically.

R1 = 200 KΩ @ 1.9V ≤ VT ≤ 4.7V

R1 = 10 Ω

@

0V ≤ VT ≤ 1.3V

6V ≤ VT ≤ Vs

muting-off

muting-on

Referringto the following input stage, the possible attenuationof the input signal and therefore of the output

signal can be found using the following expression.

AT = Vi = Rg + R5 ⁄ ⁄ R1

V5

R5 ⁄ ⁄ R1

where R5 ≅ 100 KΩ

Considering Rg = 10 KΩ the attenuation in the

muting-on condition is typically AT = 60 dB. In the

muting-off condition, the attenuation is very low,

typically 1.2 dB.

A very low current is necessary to drive the thresh-

old voltage VT because the input resistance at pin

11 is greater than 150 KΩ. The muting function can

be used in many cases,when a temporaryinhibition

of the output signal is requested, for example:

- in switch-on condition, to avoid preamplifier

power-on transients (see fig. 27)

- during commutations at the input stages.

- during the receiver tuning.

The variable impedance capability at pin 1 can be

useful in many applications and we have shown 2

examples in fig. 22 and 24, where it has been used

to change the feedback network, obtaining 2 differ-

ent frequency responses.

10/14

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