TS4997 datasheet(22/34 Pages) STMICROELECTRONICS

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Application information

TS4997

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4.5

Low frequency response

The input coupling capacitors block the DC part of the input signal at the amplifier inputs. In

the low frequency region, CIN starts to have an effect. CIN and RIN form a first-order high

pass filter with a -3dB cut-off frequency.

with RIN expressed in Ω and CIN expressed in F.

So, for a desired -3dB cut-off frequency we can calculate CIN:

From Figure 64, you can easily establish the CIN value required for a -3 dB cut-off frequency

for some typical cases.

Figure 64.

-3dB lower cut-off frequency vs. input capacitance

4.6

3D effect enhancement

The TS4997 features 3D audio effect which can be programmed at three discrete levels

(LOW, MEDIUM, HIGH) through input pins 3D1 and 3D0 which provide a digital interface.

The correspondence between the logic levels of this interface and 3D effect levels are

shown in Table 9.

The 3D audio effect applied to stereo audio signals evokes perception of spatial hearing and

improves this effect in cases where the stereo speakers are too close to each other, such as

in small handheld devices, or mobile equipment.

The perceived amount of 3D effect is also dependent on many factors such as speaker

position, distance between speakers and listener, frequency spectrum of audio signal, or

difference of signal between left and right channel. In some cases, the volume can increase

when switching on the 3D effect. This factor is dependent on the composition of the stereo

audio signal and its frequency spectrum.

π R

----------------------------------------------- Hz

()

π R

------------------------------------------------ F

()

0.2

0.4

0.6

0.8

100

Rin=24k

G~6dB

Rin=12k

G~12dB

Rin=6.2k

G~18dB

Tamb=25

°C

Input Capacitor Cin (

μF)

0.1

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