TEA7088AFP datasheet(8/17 Pages) STMICROELECTRONICS

8 / 17 page

MICROCONTROLLER INTERFACE WITH TEA7088A

All inputs can be driven by a Low level max. of

0.1 x VRMC and a high level min. of 0.9 x VRMC.

Inputs MSK, DCL and DATA have internal pull-up

resistors of 120k

Ω and input OSC has a internal

pull up of 240k

Ω.

All outputs can drive a

±1mA typical.

Power Supply

The microcontroller is power supplied by a 3.4V

regulated supply (VRMC) and by an unregulated

power supply (VMC).

The two supplies are connected through a serial

regulator.The unregulatedpower supply (VMC) has

a DC voltageequal to: V12 - 0.6V and must be lower

than 6V. It is also possible to connect a battery at

Pin VMC and use the regulated output at Pin VRMC

to supply a LCD driver.

The current consumption on the serial regulator

has a typical value of 60

µA.

Power ON (PON)

The TEA7088Ageneratesa power on signal (PON)

as soon as the voltage on Pin VRMC is higher than

2.6V (0.75 x VRMC final) and the line current is pre-

sent.

Note : D u ri ng

th e

b r eak

per i od

i n

t he

loopdisconndect and Flash mode and

during the exchange line break, the power

ON signal goes to low level. Maximum delay

for Pon decay edge after ILine goes to zero

is 50ms (with C8 = 47

µF, C11 = 1µF,

C27 = 10

µF).

Reset

The TEA7088Agenerates a rise edge Reset signal

as soon as the logic power supply is higher than

2.6V (0.75 x VRMC final).

RESET remains high until VRMC decreases below

2.5V or the RESET control code is received. In

Ring, RESET is identical to RI output.

Only new positive edge PON, derived on opening

and closing the line, is forcing the default mode

again. The Reset control code is only active in

speech mode.

Serial Bus Interface (Data and Clock)

The serial bus uses 6 bits. Astandard 8 bit bus can

be used, bits a6 and a7 are not take in account by

the TEA7088A. Different types of codes are used :

a) The Ring Control Code :

- Ring start up

- Output level codes

b) The Operating Code :

- Speech

- Dialing

- Microphone mute

- Earphone/Microphone mute

c) The Data Codes (DTMF, ring frequencies) :

Those data codes are stored inside the

TEA7088Aand are used as soon as the dialing

code or the ring start code is received.

d) The Configuration Code :

- AGC / no AGC (toggle)

- No mask / mask (Low DC in ”make”) (toggle)

- Normal gain / normal gain +6dB, on receive

channel (toggle)

- 1.79MHz external clock / 3.58MHz internal

oscillator (toggle)

Those configuration cod es are ”Flip-Flop”

codes.

For instance : The first time that the+6dB code

is sent, the receive gain increases of +6dB.

If the same code is sent again, the receive gain

goes back to normal value. In the same way the

3.58MHz internal oscillator can be switched

OFF with a second transmission of the proper

code.

e) The RESET Code :

Reset code from the MCU will reset internallogic

of TEA7088A to default mode and will induce

TEA7088A to generate a ”RESET” status ”low”

to the MCU on Pin 19.

Warning : the ”RESET” code deactivates the

serial bus interface which is reactivated only

after a ”ON-HOOK/OFF-HOOK” sequence.

f) The INITIALIZATION Code :

Initialization code from the MCU will reset the

internal logic of TEA7088A to default mode, but

the TEA7088Awill not generatereset command

to the MCU on Pin 19.

TEA7088A

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