TEA7063DP datasheet(9/15 Pages) STMICROELECTRONICS

9 / 15 page

In this condition an internal connection is acti-

vated from line DTMF output (pin 16) to Receive

Output (pin 20) with an attenuation GRS = 38.5dB

to provide acoustic feedback of the DTMF emis-

sion.

4. A.G.C AND SIDETONE PROGRAMMING

4.1 Programmable Controls

AGC and sidetone attack and disonnect points (or

currents) are programmable externally through

two independents pins, I-start (pin 9) and I-slope

(pin 15).

4.2 I-Start (pin 9)

An external resistor RLL connected between I-

start (pin 9) and Microprocessor Supply (pin 19)

controls the attack point of AGC and ZAL (an-

tisidetone Z).

ILL is the line current at which the control starts.

Formulas for ILL and RLL with R9 = 100K are:

ILL =

2880

RLL

+ 11mA

RLL =

2880

( ILL − 11mA

)

4.3 I-Slope (pin 15)

An external resistor RLS connected between

I-slope (pin 15) and Microprocessor Supply (pin

19) controls the disconnected point of AGC and

ZAS (antisidetone Z). ILS is the line current at

which the control stops. Formulas for ILS and

RLS with R9 = 100K are:

ILS =

4680

RLS

+ ILL;

RLS =

4680

( ILS − ILL

)

4.4 A.G.C. OFF (pin 9 and 15)

Programming ILL and ILS respectively higher

than 70mA and 450mA is forcing the IC in AGC

OFF Condition.

Suggested external components are:

RLL = 51K

Ω and RLS = 10KΩ

In this case sending, receiving gain and sidetone

compensation are independent of the line lenght.

Pins 1 and 2 can be connected to each other sav-

ing 5 passive external components at pin 2.

4.5 Secret Function for Private (pin 14)

The two separate thresholds for sending and Re-

ceiving Mute (pin 14) allow ”Secret Function”

(only microphone muted).

Pin 14 can be set:

a) between 0.25V and 0.8V for speech mode,

b) between 1.6V and 2.1V for ”secret” mode (mi-

crophone muted),

c) between 2.7V and 3.3V for ”all muted” mode

Figure 7

TEA7063

9/15

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