3/11

TDA7297D

specified)

3

APPLICATIVE SUGGESTIONS

STAND-BY AND MUTE FUNCTIONS

3.1 Microprocessor Application

In order to avoid annoying "Pop-Noise" during Turn-On/Off transients, it is necessary to guarantee the right St-

by and mute signals sequence.It is quite simple to obtain this function using a microprocessor (Fig. 4 and 5).

At first St-by signal (from

µP) goes high and the voltage across the St-by terminal (Pin 9) starts to increase ex-

ponentially. The external RC network is intended to turn-on slowly the biasing circuits of the amplifier, this to

avoid "POP" and "CLICK" on the outputs.

When this voltage reaches the St-by threshold level, the amplifier is switched-on and the external capacitors in

series to the input terminals (C1, C3) start to charge.

It's necessary to mantain the mute signal low until the capacitors are fully charged, this to avoid that the device

goes in play mode causing a loud "Pop Noise" on the speakers.

A delay of 100-200ms between St-by and mute signals is suitable for a proper operation.

Symbol

Parameter

Test Condition

Min.

Typ.

Max.

Unit

Supply Range

6.5

18

V

Total Quiescent Current

50

65

mA

Output Offset Voltage

120

mV

Output Power

THD 10%

8.3

10

W

THD

Total Harmonic Distortion

0.1

0.3

%

f = 100Hz to 15KHz

1%

SVR

Supply Voltage Rejection

f = 100Hz, VR =0.5V

40

56

dB

CT

Crosstalk

46

60

dB

Mute Attenuation

60

80

dB

Thermal Threshold

150

°C

Closed Loop Voltage Gain

31

32

33

dB

Voltage Gain Matching

0.5

dB

Input Resistance

25

30

K

Ω

Mute Threshold

Vo = -30dB

2.3

2.9

4.1

V

St-by Threshold

0.8

1.3

1.8

V

St-by Current

100

µA

Total Output Noise Voltage

A Curve

f = 20Hz to 20KHz

150

220

500

µV

µV