TEA1064B View Datasheet(PDF) - Philips Electronics
Part Name
Description
Manufacturer
TEA1064B Datasheet PDF : 32 Pages
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Philips Semiconductors
Low voltage versatile telephone transmission circuit
with dialler interface and transmit level dynamic limiting
Product specification
TEA1064B
handbook2, .h4alfpage
Ip
(a)
(mA)
1.6
(b)
MBA434
0.8
(a')
(b')
0
0
1
2
3 VCC (V) 4
(a) Ip = 1.94 mA
(b) Ip = 1.54 mA
(a′) Ip = 0.54 mA
(b′) Ip = 0.16 mA
Iline = 15 mA
R1 = 620 Ω and R9 = 20 Ω
Curve (a) and (a′) are valid when the receiving
amplifier is not driven or when MUTE = HIGH.
Curve (b) and (b′) are valid when the receiving
amplifier is driven and when MUTE = LOW.
Vo(RMS) = 150 mV, RT = 150 Ω.
Fig.6 Maximum current Ip with respect to Fig.5
available from Vcc for peripheral circuitry
with VCC > 2.2 V.
The maximum AC output swing on the line at low currents
is influenced by R16 (limited by current) and the maximum
output swing on the line at high currents is influenced by
DC voltage VLN-SLPE (limited by voltage). In both these
situations, the internal dynamic limiter in the sending
channel prevents distortion when the microphone is
overdriven. The maximum AC output swing on LN is
shown in Fig.7; practical values for R16 are from 200 Ω to
600 Ω and this influences both maximum output swing at
low line currents and the supply capabilities.
When the SLPE pin is the reference for peripheral circuits,
inputs MUTE, PD and DTMF must be referenced to SLPE.
This is achieved by connecting pin VEE2 to pin SLPE; VEE2
being the reference of MUTE, PD and DTMF input stages.
Active microphones can be supplied between VCC and
VEE1 as shown in Fig.5. Low power circuits that provide
MUTE, PD and DTMF inputs to the TEA1064B can also be
powered from VCC (see Fig.6 for the supply capability of
VCC). MUTE, PD and DTMF are then referenced to VEE1
and the pin VEE2 must therefore be connected to VEE1.
If the line current Iline exceeds ICC + 0.25 mA, the voltage
converter shunts the excess current to SLPE via LN;
where ICC ≈ 1.3 mA, the value required by the IC for
normal operation.
The DC line voltage on LN is:
• VLN = VLN-SLPE + (ISLPE x R9)
• VLN = Vref + ({Iline − ICC − 0.25 x 10−3 A} x R9)
in which:
• Vref = 3.23 V ± 0.25 V is the internal reference voltage
between LN and SLPE; its value can be adjusted by
external resistor RVA.
• R9 = external resistor between SLPE and VEE1 (20 Ω in
basic operation).
With R9 = 20 Ω, this results in:
• VLN = 3.3 ± 0.25 V at Iline = 15 mA
• VLN = 4.1 ± 0.3 V at Iline = 15 mA, RVA(REG-SLPE) = 33 kΩ
• VLN = 4.4 ± 0.35 V at Iline = 15mA,
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 >> (ICC + 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 audio frequency
range is shown in Fig.8.
The internal reference voltage VLN-SLPE can be increased
by external resistor RVA(REG-SLPE) connected between
REG and SLPE. The voltage VLN-SLPE is shown as a
function of RVA(REG-SLPE) in Fig.9. 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
8
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