TEA7089AFP datasheet(10/17 Pages) STMICROELECTRONICS

10 / 17 page

The Start Up Conditions of the TEA7089A

As soon as RESET is high and before sending any

code the circuit is in the following default configu-

ration :

- Speech

- No mask

- AGC ON in transmit and receive channels

- Normal gain on receive channel

- 1.79MHz input clock (oscillator in stand by)

6 bit Codes

Between two DTMF or ring frequencies, introduc-

ing a Mute or speech code implies to wait 1ms to

end the sinewave or square period.

DTMF Dialing

To dial in DTMF the following sequence of codes

must be sent :

DTMF Frequency code : 00XXXX

Dialing Mode code

: 010001

Mute or SPEECH code : 010010 or 010000

The duration of the DTMF signal is fixed by the

delay between Dialing mode code and MUTE or

SPEECH code.

Pulse Dialing

The pulse dialing function is performed by the

microcontroller through the high voltage stage.

The ”MAKE” voltage over the TEA7089A during

dialing can be reduced by sending the mask code

0010101. To recover the normal speech voltage at

the end of dialing the mask code must be sent

again.

If the mask code is not used the voltage over the

TEA7089A during dialing is the same as in speech

mode.

Ring Indicator (RI)

In ring mode TEA7089A generates a high logic

level on Pin RI as soon as the voltage on Pin VRING

is higher than VTHRI ON (19V Typ.), and the voltage

on VRMC is higher than 3.4V.

When the voltage on VRMC becomes higher than

2.6V, RESET signal becomes also high.

Mask Input (MSK)

MSK input must be high by default (Figure 10).

In speech configuration forcing MSK input to low

level will have same functionality than the MASK

code.

For ring mode when it is necessary to send other

frequencies than the 8 basic ones, this input allows

to drive the buzzer output.

MICROCONTROLLER INTERFACE WITH TEA7089A (continued)

a 0

a 2

a 5

CLK Data

Data

Synchro

Datas with a Change During CLK = 1

t0, t1, t2, t3, t4, t5 > 1

µs

Figure 9 : DATA/CLOCK Timing

MSK

P ULSE MODE

OTHER MODES

FLASH MODE

Figure 10 : MASK Timing

TEA7089A

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