TEA1064A/C1 Philips Semiconductors (Acquired by NXP), TEA1064A/C1 Datasheet - Page 13

• Manufacturer Part Number: TEA1064A/C1
• Description: TEA1064A; Low Voltage Versatile Telephone Transmission Circuit With Dialler Interface And Transmit Level Dynamic Limiting
• Manufacturer: Philips Semiconductors (Acquired by NXP)

Philips Semiconductors
The output voltage of the receiving amplifier is specified for
continuous-wave drive. Fig.16 shows the maximum output
swing of the receiving amplifier as a function of the DC
voltage drop (V
higher under speech conditions, where the ratio of the
peak to the RMS value is higher.
The gain of the receiving amplifier can be adjusted to suit
the sensitivity of the transducer used. The adjustment
range is between 20 dB and 39 dB with single-ended drive
and between 26 dB and 45 dB with differential drive. The
gain is proportional to the external resistor R4 connected
between GAR and QR . The overall gain between LN and
QR can be found by subtracting the attenuation of the
anti-sidetone network (32 dB) from the amplifier gain.
Automatic gain control input AGC
Automatic compensation of line loss is obtained by
connecting a resistor (R6) between AGC and V
automatic gain control varies the gain of the microphone
amplifier and receiving amplifier in accordance with the DC
line current. The control range is 6.1 dB; this corresponds
to a 5 km line of 0.5 mm diameter copper twisted-pair
cable (DC resistance = 176 /km, average
attenuation = 1.2 dB/km). The DTMF gain is not affected
by this feature.
March 1994
Low voltage versatile telephone transmission circuit
with dialler interface and transmit level dynamic limiting
Curve (1) is for a differential load of 47 nF (series
resistance = 100 ); f = 3400 Hz.
Curve (2) is for a differential load of 450 ; f = 1 kHz.
Curve (3) is for a single-ended load of 150
Fig.16 Maximum output swing of the receiving amplifier as a function of DC voltage drop V
receiver output as parameter: valid for both supply options; THD = 2%; I
LN
). The maximum output voltage will be
; f = 1 kHz.
EE
handbook, halfpage
V QR(rms)
. This
(V)
1.5
1.0
0.5
0
3
13
Two external capacitors (C4 =100 pF and
C7 = 10
be chosen to obtain a first-order low-pass filter. The cut-off
frequency corresponds with the time constant R4
The relationship C7 = 10
The value of R6 must be chosen with reference to the
exchange supply voltage and its feeding bridge resistance
(see Fig.17 and Table 1). Different values of R6 give the
same line current ratios at the start and the end of the
control range. If automatic line-loss compensation is not
required the AGC pin can be left open, the amplifiers then
give their maximum gain.
4
C4 = 1 nF) ensure stability. A larger value may
(1)
(2)
(3)
5
line
= 15 mA.
V LN (V)
C4 must be maintained.
MGR071
LN
6
with the load at the
Product specification
TEA1064A
C4.