TEA7092TQ Просмотр технического описания (PDF) - STMicroelectronics

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TEA7092TQ

TELEPHONE ANALOG FRONT END

STMicroelectronics 

TEA7092

MICROCONTROLLER INTERFACE (continued)

RING Mode

- Ring frequency generator :

In ring mode, to generate the ring melody in the

loudspeaker, the following sequence is sent :

• LOUDSPEAKER LEVEL : 0100XXX.

• Fi DATA : 000XXXX.

• DIVIDER DATA : 1XXXXXX.

• GROUP LISTENING CODE : 0110001.

• RING START : 0010001.

• SPEECH : 0010000 (To stop the ring mode

when off-hook is detected, PON = 1).

To change the ring frequency only Fi data and

divider data are sent again.

- Ring indicator input (RI/VI) :

In ring mode the TEA7092 generates a high logic

level on pin RI/VI, as soon as the voltage on pin

RSU is higher than 19V, and the voltage on pin

VRMC is higher than 2.6V. When the voltage on

pin VRMC is higher than 2.6V, the RESET output

goes high.

Ring Melody Control

The melody can be checked in off-hook by sending

the following sequence of codes :

- LOUDSPEAKER LEVEL : 0100XXX.

- Fi data : 000XXXX.

- DIVIDER data : 1XXXXXX.

- RING MELODY CONTROL : 0110011.

To change the melody or the level, only loud-

speaker level, Fi data and n divider data have to be

sent. To stop the ring melody, a speech code

0010000 is sent.

Figure 9 : Time Diagram of Transfer Request

Error Beep

Error beep could be used to signalize wrong opera-

tions (memory empty, re-dial empty, store too many

digits in a memory...) or for other procedures, like

melody. To generate the error beep, the following

sequence of codes is sent :

- Fi data : 000XXXX.

- DIVIDER data : 1XXXXXX.

- ERROR BEEP code : 0011100.

To stop the error beep a speech code 0010000 is

sent. The error beep is a square wave sent on the

earphone, if it is requested to send it also in the

loudspeaker, the Group listening code should also

be sent.

Line Current Variation Detection

The TEA7092 has a line current variation detector.

This feature memorizes the line current value.

When the transfer request code is sent, and if a the

current inside the TEA7092 decreases of 15% or

more of the line current value, due for example to

a telephone set off-hooked in parallel on the same

line, the output RI/VI goes HIGH to prevent the

associated microcontroller. Oscillator should be

ON, and it is preferable to mute the transmit and

receive paths to avoid current variation due to ac

signals.

- TRANSFER REQUEST : 0011010.

If the Transfer request code is sent again, the

current memorization is disabled.

Transfert Request

µP Send the Code (0011010)

RI/VI

t0

Line Current Memorization Activated

Line Current Variation

(if > 15% of IL)

Flip-Flop Operating

µP Send the Code (0011010)

RI/VI t0

Line Current Memorization Activated

Line Current Memorization Cancelled

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