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TEA7089

LOW-RANGE PHONE DEDICATED CHIP

STMicroelectronics 

TEA7089A

ELECTRICAL SPECIFICATIONS (continued)

AC Characteristics (Tamb = 25°C ; RL = 600Ω ; Logic in Default Mode unless otherwise noted)

Symbol

Parameter

Test Conditions

Min. Typ. Max. Unit

R1

Return Loss

Test 2, IL = 22mA

17

dB

f = 300/3400Hz, VAC = -10dBV

Transmit Characteristics

(Tamb = 25°C ; RL = 600Ω ; f = 1kHz ; Logic in Default Mode unless otherwise noted)

Symbol

Gtx

Gtxl

Gtxs

Zmic

Ntx

Parameter

Microphone Gain

Microphone Input Impedance

Noise

Mmic

Dtx

VL Max.

Microphone Mute

Soft Clipping

- Distortion

- Maximum Level on Line

Test Conditions

Test 3, Vm = -55dBV

R8 = 1.3kΩ, R25 = 3.9kΩ

IL = 22mA

IL = 90mA

between MIC1 & MIC2

Test 3, 2kΩ on microphone inputs,

IL = 22mA

Test 3, Vm = -55dBV, IL = 22mA

Test 3, IL = 22mA, see Figure 2

Vm = -41dBV

Vm = -34dBV

Min. Typ.

45 46

38 40

32 40

-76

60

1.5

Max.

47

42

48

2

Unit

dB

dB

kΩ

dBmp

dB

%

Vp

Figure 2 : Softclipping

10

Thres hold

Le ve l

1

0.1

0.1

Figure 3

10

8

1

10

Vmicrophone pe a k (mV)

6

4

2 VAC pe a k

0

0

20

40

60

IL (mA)

-15

-10

-5

-2

100

VAC pe a k

80

100

The maximum gain Gtl is adjustable between 44

and 56dB with R8 :

Gtxl

=

20log

820



⋅

R1R08///R/ 5L0+kΩR11

The AGC variation is programmed with one resistor

connected on Pin AGC. ISL is the line current at

which the gain must be decreased by 6dB.

R25

(Ω)

=

300

ISL − 5mA

(R25

>

2.6kΩ)

For line current lower than ILL or higher than ISL,

The transmit and receive gains have a constant

value.

If no resistor or a resistor higher than 300kΩ is

connected on Pin AGC, the gain is constant and

equal to Gtxl and Grxl. ±0.5dB.

AGC can be inhibited also through MCU code

”010100”. In this case Tx and Rx gains are fixed

2dB lower than the maximum gain.

The minimum saturation voltage of the TEA7089A

respect to ground is 2.2V. On long line, when the

voltage over TEA7089A is low, the softclipping

function automatically limits the AC dynamic to

avoid to reach the 2.2V limit on TEA7089A respect

to ground.

5/17

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