TEA7092 ST Microelectronics, Inc., TEA7092 Datasheet - Page 7

• Manufacturer Part Number: TEA7092
• Description: Telephone Analog Front End
• Manufacturer: ST Microelectronics, Inc.

TRANSMIT CHARACTERISTICS (continued)
Maximum Level on Line in Tx (see Figure 3)
The minimum operating voltage of the TEA7092 is 2.5V. At low line current value, when the voltage over
the TEA7092 is low, the softclipping function automatically limits the AC dynamic to avoid to reach the 2.5V
limit on the TEA7092.
When the DC voltage over the TEA7092 is high enough, the AC dynamic is limited at a value fixed by the
external resistor RSOFT connected on Pin SOFTL.
The Value of RSOFT is performed by : RSOFT = (RS x 50E
Tx Characteristics (T
Squelch on Transmit Channel (T
The principle of the squelch is to reduce the transmit gain as soon as the amplitude of the signal on the
microphone is lower than a fixed threshold voltage, VT2.
Figure 3 :
Gtlmax-Gsq
Symbol
Gt-6dB
V
Ghfm
Symbol
Gtsm
Mmic
Zmic
Dtx1
Dtx2
Gtlmax
Ghl
Zhf
Ntx
Nhf
Gtl
Lpeak
Gsq
Transmit gain in Handset Mode
Transmit gain in Handsfree Mode
Transmit Gain
(-6dB in transmit path)
Handset Mic Input Impedance
Handsfree Mic Input Impedance
Transmit Noise in Handset Mode
Transmit Noise in Handsfree Mode
Microphone Mute
Transmit Softclipping Level
Transmit Distortion
Transmit Gain
Gain Variation
Line Peak Voltage versus DC Line
Current
Parameter
amb
Parameter
= 25°C, f = 1kHz, see Test 3)
amb
= 25°C, f = 1kHz, I
V
V
V
Code 0110110
Between Pins MIC1, MIC2
Between HFIN and V
I
V
See Figure 2, V
I
L
L
em
hfin
em
em
= 20mA, Code 0110010
= 20mA, see Figure 2
V
V
See Figure 4 /
I
I
I
I
2k
2k
V
V
em1
em2
L
L
L
L
= -48dBV
= -48dBV, I
= -48dBV, I
= -28dBV, Code 0110010
em
em
= 20mA
= 90mA
= 20mA
= 90mA
= -75dBV
= -65dBV
= -48dBV
= -36dBV
between MIC1 & MIC2
between HFIN & V
Test Conditions
Test Conditions
Figure 4 :
L
em
L
L
= 20mA
= 20mA
= 20mA, see Test3)
= -42dBV, I
-6
- 0.8 - VacPeak) / 40E
REF
REF
Transmit Gain versus Microphone
AC Input Signal
L
= 20mA
Min.
Min.
1.0
44
37
24
17
30
15
60
5
Typ.
36
45
-6
9
Typ.
-75
-75
1.4
45
39
25
19
40
20
6
Max.
Max.
1.8
46
41
26
21
50
25
7
1
5
TEA7092
Vpeak
dBmp
dBmp
Unit
Unit
dB
dB
dB
dB
dB
dB
dB
dB
k
k
dB
%
%
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