INTEGRATED CIRCUITS
DATA SHEET
TEA1064A
Low voltage versatile telephone transmission circuit with dialler interface and transmit level dynamic limiting
Product specification |
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March 1994 |
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File under Integrated Circuits, IC03A |
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Philips Semiconductors |
Product specification |
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Low voltage versatile telephone transmission circuit
TEA1064A
with dialler interface and transmit level dynamic limiting
GENERAL DESCRIPTION
The TEA1064A is a bipolar integrated circuit that performs all the speech and line interface functions required in fully electronic telephone sets. It performs electronic switching between dialling and speech and has a powerful DC supply for peripheral circuits. The IC operates at line voltages down to 1.8 V DC (with reduced performance) to facilitate the use of more telephone sets connected in parallel. The transmit signal on the line is dynamically limited (speech-controlled) to prevent distortion at high transmit levels of both the sending signal and the sidetone.
FEATURES
∙Low DC line voltage; operates down to 1.8 V (excluding polarity guard)
∙Voltage regulator with low voltage drop and adjustable static resistance
∙DC line voltage adjustment facility
∙Provides a supply for external circuits in two options: unregulated supply, regulated line voltage;
stabilized supply, line voltage varies with supply current
∙Dynamic limiting (speech-controlled) in transmit direction prevents distortion of line signal and sidetone
∙Symmetrical high-impedance inputs (64 kΩ) for dynamic, magnetic or piezo-electric microphones
∙Asymmetrical high-impedance input (32 kΩ) for electret microphones
∙DTMF signal input
∙Confidence tone in the earpiece during DTMF dialling
∙Mute input for disabling speech during pulse or DTMF dialling
∙Power-down input for improved performance during pulse dial or register recall (flash)
∙Receiving amplifier for magnetic, dynamic or piezo-electric earpieces
∙Large amplification setting ranges on microphone and earpiece amplifiers
∙Line loss compensation (line current dependent) for microphone and earpiece amplifiers (not used for DTMF amplifier)
∙Gain control curve adaptable to exchange supply
∙Automatic disabling of the DTMF amplifier in extremely-low voltage conditions
∙Microphone MUTE function available with switch
PACKAGE OUTLINES
TEA1064A :20-lead DIL; plastic (SOT146).(1)
TEA1064AT:20-lead mini-pack; plastic (SO20; SOT163A).(2)
Notes
1.SOT146-1; 1998 Jun 18.
2.SOT163-1; 1998 Jun 18.
March 1994 |
2 |
Philips Semiconductors |
Product specification |
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Low voltage versatile telephone transmission circuit
TEA1064A
with dialler interface and transmit level dynamic limiting
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VCC1 |
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LN |
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16 |
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1 |
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13 |
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6 |
GAR |
IR |
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5 |
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− |
+ |
QR+ |
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TEA1064A |
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+ |
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4 |
QR− |
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19 |
VCC2 |
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9 |
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2 |
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MIC+ |
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+ |
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GAS1 |
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MIC− |
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+ |
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+ |
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12 |
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3 |
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DTMF |
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dB |
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GAS2 |
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− |
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MUTE |
14 |
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PD |
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SUPPLY AND |
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REFERENCE |
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AGC |
LOW |
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VOLTAGE |
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CIRCUIT |
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CIRCUIT |
DYNAMIC |
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LIMITER |
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CURRENT |
START |
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REFERENCE |
CIRCUIT |
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11 |
17 |
18 |
10 |
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7 |
20 |
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VEE |
REG |
AGC |
STAB |
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DLS/MMUTE |
SLPE |
MGR056 |
Fig.1 Block diagram.
March 1994 |
3 |
Philips Semiconductors |
Product specification |
|
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Low voltage versatile telephone transmission circuit
TEA1064A
with dialler interface and transmit level dynamic limiting
QUICK REFERENCE DATA
PARAMETER |
CONDITIONS |
SYMBOL |
MIN. |
TYP. |
MAX. |
UNIT |
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Operating ambient temperature |
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range |
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Tamb |
−25 |
− |
+ 75 |
°C |
Line current operating range: |
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normal operation |
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l |
11 |
− |
140(1) |
mA |
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line |
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with reduced performance |
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lline |
2 |
− |
11 |
mA |
Internal supply current: |
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power-down input LOW |
VCC1 = 2.8 V |
ICC1 |
− |
1.3 |
1.6 |
mA |
power-down input HIGH |
VCC1 = 2.8 V |
ICC1 |
− |
60 |
82 |
μA |
Voltage gain range: |
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microphone amplifier |
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Gv |
44 |
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52 |
dB |
receiving amplifier |
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Gv |
20 |
− |
45 |
dB |
Line loss compensation: |
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gain control range |
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Gv |
5.7 |
6.1 |
6.5 |
dB |
exchange supply voltage |
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range |
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Vexch |
36 |
− |
60 |
V |
exchange feeding bridge |
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resistance range |
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Rexch |
400 |
− |
1000 |
Ω |
Maximum output voltage swing |
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on LN (peak-to-peak value) |
R15 + R16 = 448 Ω |
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lline = 15 mA |
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Ip = 2 mA |
VLN(p-p) |
3.7 |
3.95 |
4.2 |
V |
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Ip = 4 mA |
VLN(p-p) |
3.0 |
3.25 |
3.5 |
V |
Regulated line voltage application |
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R15 = 0 Ω; |
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R16 = 392 Ω |
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Supply for peripherals |
lline = 15 mA |
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Ip = 1.4 mA |
Vp |
2.5 |
− |
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V |
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Ip = 2.7 mA; |
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RREG-SLPE = 20 kΩ |
Vp |
2.9 |
− |
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V |
DC line voltage |
lline = 15 mA |
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without RREG-SLPE |
VLN |
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3.57 |
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V |
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RREG-SLPE = 20 kΩ |
VLN |
− |
4.57 |
− |
V |
March 1994 |
4 |
Philips Semiconductors |
Product specification |
|
|
Low voltage versatile telephone transmission circuit
TEA1064A
with dialler interface and transmit level dynamic limiting
PARAMETER |
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CONDITIONS |
SYMBOL |
MIN. |
TYP. |
MAX. |
UNIT |
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Stabilized supply voltage application |
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R15 |
= 392 Ω; |
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R16 |
= 56 Ω |
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Supply for peripherals |
lline = 15 mA |
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Ip = 0 to 4 mA |
VCC2-SLPE |
3.05 |
3.3 |
3.55 |
V |
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DC line voltage |
lline = 15 mA |
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Ip = 2 mA |
VLN |
4.2 |
4.4 |
4.8 |
V |
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Ip = 4 mA |
VLN |
4.9 |
5.1 |
5.5 |
V |
Note
1. For TEA1064AT the maximum line current depends on the heat dissipating qualities of the mounted device.
PINNING
handbook, halfpage |
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LN |
1 |
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20 |
SLPE |
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VCC2 |
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GAS1 |
2 |
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19 |
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GAS2 |
3 |
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18 |
AGC |
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QR− |
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4 |
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17 |
REG |
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QR+ |
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VCC1 |
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5 |
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16 |
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GAR |
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TEA1064A |
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PD |
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6 |
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15 |
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DLS/MMUTE |
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14 |
MUTE |
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MIC− |
8 |
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IR |
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13 |
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MIC+ |
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DTMF |
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12 |
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STAB 10 |
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VEE |
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11 |
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MGR057 |
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Fig.2 Pinning diagram.
1 |
LN |
positive line terminal |
2 |
GAS1 |
gain adjustment; transmitting amplifier |
3 |
GAS2 |
gain adjustment; transmitting amplifier |
4 |
QR− |
inverting output, receiving amplifier |
5 |
QR+ |
non-inverting output, receiving |
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amplifier |
6 |
GAR |
gain adjustment; receiving amplifier |
7 |
DLS/ |
decoupling for transmit amplifier |
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MMUTE |
dynamic and microphone MUTE input |
8 |
MIC− |
inverting microphone input |
9 |
MIC+ |
non-inverting microphone input |
10 |
STAB |
current stabilizer |
11 |
VEE |
negative line terminal |
12 |
DTMF |
dual-tone multi-frequency input |
13 |
IR |
receiving amplifier input |
14 |
MUTE |
mute input |
15 |
PD |
power-down input |
16 |
VCC1 |
internal supply decoupling |
17 |
REG |
voltage regulator decoupling |
18 |
AGC |
automatic gain control input |
19 |
VCC2 |
reference voltage with respect to SLPE |
20 |
SLPE |
slope adjustment for DC |
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curve/reference for peripheral circuits. |
March 1994 |
5 |
Philips Semiconductors |
Product specification |
|
|
Low voltage versatile telephone transmission circuit
TEA1064A
with dialler interface and transmit level dynamic limiting
FUNCTIONAL DESCRIPTION
Supplies VCC1, VCC2, LN, SLPE, REG and STAB (Fig.3)
Power for the TEA1064A and its peripheral circuits is usually obtained from the telephone line. The IC develops its own supply voltage at VCC1 and regulates its voltage drop. The internal supply requires a decoupling capacitor between VCC1 and VEE. The internal current stabilizer is set by a 3.6 kΩ resistor between STAB and VEE.
The DC current flowing into the set is determined by the exchange supply voltage Vexch, the feeding bridge
resistance Rexch, the subscriber line DC resistance Rline and the DC voltage (including polarity guard) on the
subscriber set (see Fig.3).
The internal voltage regulator generates a temperature-compensated reference voltage that is available between VCC2 and SLPE
[Vref = VCC2-SLPE = 3.3 V (typ.)]. This internal voltage regulator requires decoupling by a capacitor between REG
and VEE (C3).
The reference voltage can be used to:
∙regulate directly the line voltage (stabilized
VLN-SLPE = VCC2-SLPE)(1)
∙to stabilize the supply voltage for peripherals.
Regulated line voltage
In this application the VCC2 pin is connected to the LN pin as shown in Fig.3. This configuration gives a stabilized
voltage across pins LN and SLPE which, applied via the low-pass filter R16, C15, provides a supply to the peripherals that is independent of the line current and depends only on the peripheral supply current.
The value of R16 and the level of the DC voltage VLN-SLPE determine the supply capabilities. In the basic application
R16 = 392 Ω and C15 = 220 μF. The worst-case peripheral supply current as a function of supply voltage is shown in Fig.4. To increase the supply capabilities, the DC
voltage VLN-SLPE can be increased by using RVA(REG-SLPE) or by decreasing the value of R16.
(1)The TEA1064A application with regulated line voltage is the same as is used for TEA1060/TEA1061, TEA1067 and TEA1068 integrated circuits.
handbook, full pagewidth |
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Ip + 0.25 mA |
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Rline |
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I |
line |
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R1 |
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ISLPE |
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ICC1 |
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LN |
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VCC1 |
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TEA1064A |
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1 |
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16 |
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V |
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Rexch |
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19 |
CC2 |
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DC |
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0.25 mA |
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C1 |
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R16 |
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Vexch |
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AC |
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11 |
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REG |
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STAB |
SLPE |
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VEE |
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C3 |
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R5 |
R9 |
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C15 |
peripheral |
Vp |
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circuits |
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MGR058 |
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The voltage VLN-SLPE is fixed to Vref = 3.3 ± 0.25 V. Resistor R16 together with the line current determine the supply capabilities and the maximum output swing on
the line (no loop damping is necessary).
The line voltage VLN = Vref + ([Iline − 1.55 mA] × R9).
Fig.3 Application with regulated line voltage (stabilized VLN-SLPE).
March 1994 |
6 |
Philips Semiconductors |
Product specification |
|
|
Low voltage versatile telephone transmission circuit
TEA1064A
with dialler interface and transmit level dynamic limiting
5 |
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MGR059 |
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handbook, halfpage |
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Ip |
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(mA) |
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4 |
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3 |
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R |
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VA |
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(REG |
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2 |
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- |
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SLPE) |
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R |
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= |
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VA |
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20 |
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1 |
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without |
k |
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Ω |
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(REG |
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- |
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SLPE) |
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0 |
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3 |
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4 |
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2 |
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Vp (V) |
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lline = 15 mA; R16 = 392 Ω; R15 = 0 Ω; valid for MUTE = 0 and 1. Line current has very little influence
Fig.4 Minimum supply current for peripherals (Ip) as a function of the peripheral supply voltage (Vp).
The maximum AC output swing on the line at low line currents is influenced by R16 (limited by current) and the maximum output swing on the line at high line currents is influenced by the DC voltage VLN-SLPE (limited by voltage). In both these situations, the internal dynamic limiter in the sending channel prevents distortion when the microphone input is overdriven. The maximum AC output swing on LN is shown in Fig.5; practical values for R16 are from 200 to 600 Ω and this influences both the maximum output swing at low line currents and the supply capabilities.
The SLPE pin is the ground reference for peripheral circuits, therefore inputs MUTE, PD and DTMF are also referenced to SLPE.
Active microphones can be supplied between VCC1 and VEE. Low-power circuits that provide only MUTE and/or PD inputs to the TEA1064A also can be powered from VCC1. However VCC1 cannot be used for circuits that provide DTMF signals to the TEA1064A because VCC1 is referred to ground.
If the line current lline exceeds ICC1 + 0.25 mA, the voltage converter shunts the excess current to SLPE via LN;
where ICC1 ≈ 1.3 mA, the value required by the IC for normal operation.
The DC line voltage on LN is:
VLN = VLN-SLPE + (ISLPE × R9)
VLN = Vref + ([Iline − ICC1 − 0.25 × 10−3 A] × R9)
in which
Vref = 3.3 V ± 0.25 V is the internal reference voltage
between VCC2 and SLPE; its value can be adjusted by external resistor RVA
R9 = external resistor between SLPE and VEE (20 Ω in basic application).
With R9 = 20 Ω, this results in:
VLN = 3.57 ± 0.25 V at lline = 15 mA
VLN = 4.17 ± 0.3 V at lline = 15 mA,
RVA(REG-SLPE) = 33 kΩ
VLN = 4.57 ± 0.35 V at lline = 15 mA,
RVA(REG-SLPE) = 20 kΩ
The preferred value for R9 is 20 Ω. Changing R9 influences microphone gain, DTMF gain, the gain control characteristics, sidetone, and the DC characteristics (especially the low voltage characteristics).
In normal conditions, ISLPE >> (ICC1 + 0.25 mA) and the static behaviour is equivalent to a voltage regulator diode
with an internal resistance of R9. In the audio frequency range the dynamic impedance is determined mainly by R1. The equivalent impedance of the circuit in the audio frequency range is shown in Fig.6.
The internal reference voltage VCC2-SLPE can be increased by external resistor RVA(REG-SLPE) connected between
REG and SLPE. The supply voltage VCC2-SLPE is shown as a function of RVA(REG-SLPE) in Fig.7. Changing the reference voltage influences the output swing of both
sending and receiving amplifiers.
At line currents below 8 mA (typ.), the DC voltage dropped across the circuit is adjusted to a lower level automatically (approximately 1.8 V at 2 mA). This gives the possibility of operating more telephone sets in parallel with DC line voltages (excluding polarity guard) down to an absolute minimum of 1.8 V. At line currents below 8 mA (typ.), the circuit has limited sending and receiving levels.
March 1994 |
7 |
Philips Semiconductors |
Product specification |
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Low voltage versatile telephone transmission circuit
TEA1064A
with dialler interface and transmit level dynamic limiting
6 |
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MGR060 |
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VLN(p-p) |
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handbook, halfpage |
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LN |
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4 |
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Leq |
Rp |
R1 |
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Vref |
REG |
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Ip = |
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4 mA |
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VEE |
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Fig.6 |
Equivalent impedance between LN and |
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VEE in the application with stabilized |
Fig.5 Maximum AC output swing on the line as a |
VLN-SLPE: |
function of line current with peripheral |
R15 = 0 Ω |
supply current as a parameter: R15 = 0 Ω; |
Leq = C3 × R9 × Rp |
R16 = 392 Ω. |
Rp = 15 kΩ |
handbook, full pagewidth |
7.8 |
MGR062 |
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Vref
(V)
6.6
5.4
4.2
with RVA infinite
3.0
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40 |
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120 |
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RVA (REG-SLPE) (kΩ) |
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Fig.7 Internal reference voltage VCC2-SLPE as a function of resistor RVA(REG-SLPE) for line currents between 11 and 140 mA.
In the stabilized supply application:
VLN = VCC2-SLPE + ([Ip + 0.25 × 10−3 A] × R15) + ([Iline − 1.55 × 10−3 A] × R9)
In the unregulated supply application (R15 = 0 Ω):
VLN = VCC2-SLPE + ([Iline − 1.55 × 10−3 A] × R9)
March 1994 |
8 |
Philips Semiconductors |
Product specification |
|
|
Low voltage versatile telephone transmission circuit
TEA1064A
with dialler interface and transmit level dynamic limiting
Stabilized peripheral supply voltage
The configuration shown in Fig.8 provides a stabilized voltage across pins VCC2 and SLPE for peripheral circuits (such as dialling and control circuits); the DC voltage VLN now varies with the peripheral supply current.
The VCC2-SLPE supply must be decoupled by capacitor C15. For stable loop operation, resistor R16 (» 50 W) is
connected between VCC2 and SLPE in series with C15. The voltage regulator control loop is completed by resistor R15 between LN and VCC2.
For sets with an impedance of 600 W, practical values are: R15 = 200 to 600 W; C15 = 220 mF; C3 = 470 nF. The ratio R15/R16 £ 8 is for stable loop operation with sufficient phase margin, and R15/R16 ³ 6 is for satisfactory set impedance in the audio frequency range.
For sets with complex impedance, the value of C3 and the ratio R15/R16 are different (further information is given in the TEA1064A Application Report(1)).
The peripheral supply capability depends mainly on the available line current, the required AC output swing on the line, the maximum permitted DC voltage on the line and
the values of external components (especially R15). With R15 = 392 W and R16 = 56 W (basic application) the maximum possible AC output swing on the line as a function of line current is as shown in Fig.9, the curve parameter is the peripheral supply current (Ip). Different values for R15 (from 200 to 600 W) maintaining
6 < R15/R16 < 8 give different results (these are described in the TEA1064A Application Report (1).
(1) Supplied on request.
handbook, full pagewidth |
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TEA1064A |
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C15 |
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MGR063 |
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Fig.8 Application with stabilized supply voltage for peripheral circuits: R15 = 392 W; R16 = 56 W.
March 1994 |
9 |
Philips Semiconductors |
Product specification |
|
|
Low voltage versatile telephone transmission circuit
TEA1064A
with dialler interface and transmit level dynamic limiting
The DC line voltage on LN is
VLN = VLN-SLPE + (ISLPE × R9).
Therefore
VLN = Vref + ([Ip + 0.25 × 10-3 A] × R15) +
([lline − ICC1 − 0.25 × 10-3 A] × R9)
in which:
Vref is the internal reference voltage between VCC2 and SLPE (the value of Vref can be adjusted by an external resistor, RVA). Vref = 3.3 V (typ.) without RVA
Ip is the supply current used by peripheral circuits
R15 is an external resistor between LN and VCC2 (392 Ω in the basic application)
R9 is an external resistor between SLPE and VEE (20 Ω in the basic application)
8 |
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MGR064 |
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handbook, halfpage |
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VLN(p-p) |
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Ip = 4 mA |
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(V) |
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2 mA |
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10 |
20 |
Iline (mA) |
30 |
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As different values of R15 and R16 are allowed, different curves would then apply
Fig.9 Maximum output swing on line as a function of line current with the peripheral supply current as a parameter; R15 = 392 Ω;
R16 = 56 Ω.
The DC voltage VLN-SLPE as a function of Ip with R15 as a parameter is shown in Fig.10. In the audio frequency
range, the dynamic impedance is determined mainly by R1. The equivalent impedance in the audio range of the circuit (Fig.8) is shown in Fig.11.
MGR065
5.5 handbook, halfpage
VLN-SLPE
(V)
5.0
R15 = 511 W
392 W
4.5
301 W
4.0
3.5
3.0
0 |
1 |
2 |
3 |
4 |
Ip (mA)
VCC2-SLPE can be adjusted between approximately 3.3 and 4.3 V by changing the value of RVA, this results in a parallel-shift of the curves.
The total voltage drop VLN » VLN-SLPE + ([Iline - 1.55 mA] ´ R9).
Fig.10 Curves showing the typical voltage drop between LN and SLPE as a function of the supply current for peripherals with R15 as a
parameter: VCC2-SLPE = 3.3 V (RVA not connected).
handbook, halfpage |
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Leq |
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R1 |
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R9 |
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C3 |
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620 W |
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20 W |
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470 nF |
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VEE |
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MGR066 |
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æ R15 |
1 |
ö |
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eq |
---------- + |
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p è R16 |
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Leq |
= C3 ´ R9 ´ Req with Rp= 15 kW |
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Fig.11 Equivalent impedance between LN and VEE at f > 300 Hz in the application with stabilized supply voltage for peripheral circuits.
March 1994 |
10 |
Philips Semiconductors |
Product specification |
|
|
Low voltage versatile telephone transmission circuit
TEA1064A
with dialler interface and transmit level dynamic limiting
Microphone inputs MIC+ and MIC− and gain pins
GAS1 and GAS2
The TEA1064A has symmetrical microphone inputs, its input impedance is 64 kΩ (2 × 32 kΩ) and its voltage amplification is typ. 52 dB with R7 = 68 kΩ. Either dynamic, magnetic or piezo-electric microphones can be used, or an electret microphone with a built-in FET buffer. Arrangements for the microphone types are shown in Fig.12.
The gain of the microphone amplifier is proportional to external resistor R7 connected between GAS1 and GAS2 and with this it can be adjusted between 44 dB and 52 dB to suit the sensitivity of the transducer.
An external 100 pF capacitor (C6) is required between GAS1 and SLPE to ensure stability. A larger value of C6 may be chosen to obtain a first-order low-pass filter with a cut-off frequency corresponding to the time constant
R7 × C6.
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VCC1 |
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MIC+ |
MIC− |
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MIC+ |
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(1)
MIC− |
MIC+ |
MIC− |
8 |
9 |
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11 |
VEE
MGR067
(a) |
(b) |
(c) |
Fig.12 Microphone arrangements: a) magnetic or dynamic microphone, the resistor (1) may be connected to reduce the terminating impedance, or for sensitive types a resistive attenuator can be used to prevent overloading the microphone inputs; b) electret microphone; c) piezo-electric microphone.
Dynamic limiter (microphone) pin DLS/MMUTE
A low level at the DLS/MMUTE pin inhibits the microphone inputs MIC+ and MIC− but has no influence on the receiving and DTMF amplifiers.
Removing the low level at the DLS/MMUTE pin provides the normal function of the microphone amplifier after a short time determined by the capacitor connected to DLS/MMUTE pin. The microphone mute function can be realised by a simple switch as shown in Fig.13.
To prevent distortion of the transmitted signal, the gain of the sending amplifier is reduced rapidly when peaks of the signal on the line exceed an internally-determined threshold. The time in which gain reduction is effected (attack time) is very short. The circuit stays in the gain-reduced condition until the peaks of the sending signal remain below the threshold level. The sending gain then returns to normal after a time determined by the capacitor connected to DLS/MMUTE (release time).
The internal threshold adapts automatically to the DC voltage setting of the circuit (voltage VLN-SLPE). This
means that the maximum output swing on the line will be higher if the DC voltage dropped across the circuit is increased.
Fig.14 shows the maximum possible output swing on the
line as a function of the DC voltage drop (VLN-SLPE) with Iline − Ip as a parameter.
handbook, halfpage
DLS/MMUTE 7
R17
3.3 kΩ
VEE
11
MGR068
Fig.13 Microphone-mute function.
March 1994 |
11 |