Document
TEA7089A
LOW-RANGE PHONE DEDICATED CHIP
. . . . . . .
RING - GENERATION OF 8 MELODY TONES (Including the 3 German Melody Tones) - 4 STEPS DIGITAL CONTROL ON THE AMPLIFIER OUTPUT LEVEL SPEECH - TRANSMIT GAINEXTERNALLY ADJUSTABLE - RECEIVINGGAINEXTERNALLYADJUSTABLE - AGCSLOPEEXTERNALLYPROGRAMMABLE - SOFTCLIPPING ON SENDING CHANNEL - RECEIVE AMPLIFIER FOR PIEZO OR ELECTRODYNAMIC TRANSDUCER - +6dB MODE ON RECEIVE CHANNEL - LINE POWER MANAGEMENT DIALING - DTMF GENERATOR - LOW DC MASK DURING MAKE PERIOD THROUGH MICROCONTROLLER SERIAL BUS INTERFACE MICROCONTROLLER INTERFACE - 1.79MHz CLOCK OR 3.58MHz OSCILLATOR INPUT MICROCONTROLLER POWER SUPPLY MICROCONTROLLER CONTROL INTERFACE INCLUDING SERIAL BUS LINE CURRENT EXTRACTOR FOR SUPPLY OF EXTERNAL PERIPHERALS
SO28 (Plastic Package) ORDER CODE : TEA7089AFP
PIN CONNECTIONS
S OFT
1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 27 26 25 24 23 22 21 20 19 18 17 16 15
DTMF
RECIN SN AGC MIC1
MIC2
VREF VRMC
DCL DATA
MSK OSC RI
P ON
GTR
DESCRIPTION The TEA7089A is a Telephone Analog Front End device, TAFE, which integrates the three basic functions of a standard telephone set : - Speech network, - DTMF generator, - Ringer generator on buzzer. A complete telephone set can be designed using TEA7089A associated with a low cost microcontroller.
June 1998
VCC GND IVLS
VS
RES
VRING BUZ
7089A-01.EPS
VL VMC GREC
EAR+
EAR-
1/17
TEA7089A
SPEECH The speech network includes : - a low noise transmit channel suitable for any kind of microphone transducer. Softclipping on transmit line signal is provided by the chip. - a low noise receive channel with symmetrical outputs to be compatible with both piezoceramic and electrodynamic earpiece. An additional 6dB gain can be inserted in the receive channel through software control. - a line length gain control (AGC) with starting point of gain regulation fixed at 25mAline current ; slope of gain regulationis externallyadjustablewith one resistor.AGC can be removedby hardware (maximum gain flat) or by software (-2dB flat). The phone impedance and sidetone can be tuned through external networks. DTMF GENERATOR The onboard DTMF generator fullfils the CEPT requirements with an external single pole filter. PIN DESCRIPTION
Name SOFT RECIN SN AGC MIC1 MIC2 GTR VCC GND IVLS VS VL V MC GREC EAREAR+ BUZ VRING RES PON RI OSC MSK DATA DCL VRMC VREF DTMF 2/17 Pin N ° 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Description Transmit Softclipping Time Constant Receiving Input Sidetone Network Input Line Current Regulation Stop Value Microphone Input Microphone Input Transmit Gain Adjustment Transmit and Receive Part Power Supply Ground Line Current Source Power Supply Voltage Stabilizer Positive Line Unregulated Microcontroller Power Supply Receive Gain Adjustment Negative Earphone Output Positive Earphone Output Ringer Buzzer Output Ring Power Supply Reset Power On Ring Indicator Oscillator Input Mask, Ring Melody Input Data Input Data Clock Input Microcontroller Stabilized Power Supply Reference Voltage (VCC/2) DTMF Filter
RINGER Up to 8 different tones can be generated by the TEA7089Aringer. The digital volume control of the ringer can be performed through a specific command (4 steps). A ring indication signal is provided to the microcontroller by the TEA7089A.If more tones are requested the input RM/MSK allows to inject tones generated by the microcontroller. FURTHER ADVANTAGES The microcontroller power supply is provided by the TEA7089A.The power supply is specifically designed to copewitha longflash or a long groundkey duration. The TEA7089A is able to supply the necessary current to an external speakerphone circuit TEA7540 and loudspea ker amplifier TEA7532 without any additional circuitry. Line current and reset indications are provided to the microcontroller by the TEA7089A. The microcontroller drives the TEA7089A through a 2 wires serial interface.
7089A-01.TBL
To Line C8 C30 To µP To Line C1 C12 VL RI
21 12 8 10 2 3
R10 R13 VCC Sidetone
R11
R12
VCC
IVLS
RECIN
SN
C11
Figure 1 : Block Diagram
VS
11
TEA7089A
18 26 17
R40 + R15 C16 C15
VREF VSTAB RING POWER SUPPLY LOGIC POWER SUPPLY BUZZER AMPLIFIER LINE CURRENT POWER SUPPLY
27
VREF
C14
R14
VRING VRMC BUZ
GREC
14
R17 MUTE AGC MUTE CONTROL
SIDETONE & AGC
EAR+
16
Earphone
Earphone Amplifier -1 SERIAL REGULATOR
EAR-
15
RING GENERATOR
13
VMC
C10
C3 KVL
R4
SOFT
1
R8
VIN
GTR
DTMF GENERATOR µP INTERFACE AGC VREF PON & RESET CONTROL OSCILLATOR /2
7
23 MSK 25 DCL 24 DATA
MIC1
5
To µP
Microphone
MIC2
6
4 9
28
20
19
22
C3 AGC DTMF
GND
PON To µP
RES
OSC
VCC R25
TEA7089A
3/17
7089A-02.EPS
TEA7089A
ELECTRICAL CHARACTERISTICS The block diagram is given in Figure 1. The values of the different networks used in this datasheet are defined as followed : - The return loss is adjusted by R10 of 600Ω. - The transmit adjust gain network R8 is calculated in order to have a gain of 46dB typical with ILS = 22mA. - The sidetone net.