ELECTRICAL CHARACTERISTICS (Continued)

Symbol

Parameter

Test Condition

Min.

Typ.

Max.

Unit

St-by Threshold

0.8

1.3

1.8

V

ST-BY current V6 = GND

100

µA

Total Output Noise Voltage

A curve

f = 20Hz to 20kHz

150

µV

APPLICATION SUGGESTION

STAND-BY AND MUTE FUNCTIONS

(A) Microprocessor Application

In order to avoid annoying "Pop-Noise" during

Turn-On/Off transients, it is necessary to guaran-

tee the right St-by and mute signals sequence.

It is quite simple to obtain this function using a mi-

croprocessor (Fig. 1 and 2).

At first St-by signal (from mP) goes high and the

voltage across the St-by terminal (Pin 7) starts to

increase exponentially. 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 (C3,

C5) 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.

(B) Low Cost Application

In low cost applications where the

µP is not pre-

sent, the suggested circuit is shown in fig.3.

The St-by and mute terminals are tied together

and they are connected to the supply line via an

external voltage divider.

The device is switched-on/off from the supply line

and the external capacitor C4 is intended to delay

the St-by and mute threshold exceeding, avoiding

"Popping" problems.

(mV)

pin 7

(mA)

ST-BY

MUTE

PLAY

MUTE

ST-BY

+18

1.8

0.8

pin 6

4.1

2.3

OFF

OFF

D96AU259

(V)

2.9

1.3

Figure 1: Microprocessor Driving Signals.

TDA7266L

3/7