TEA7088A 데이터 시트보기 (PDF) - STMicroelectronics
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TEA7088A Datasheet PDF : 17 Pages
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TEA7088A
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 TEA7088A
respect to ground is 2.2V. On long line, when the
voltage over TEA7088A is low, the softclipping
function automatically limits the AC dynamic to
avoid to reach the 2.2V limit on TEA7088A respect
to ground.
5/17
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