TEA1064A/C1 Philips Semiconductors (Acquired by NXP), TEA1064A/C1 Datasheet - Page 12

• 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 internal threshold level is lowered automatically if the
DC current in the transmit output stage is insufficient. This
prevents distortion of the sending signal in applications
using parallel-connected telephones or telephones
operating over long lines, for example.
Dynamic limiting also considerably improves sidetone
performance in over-drive conditions (less distortion;
limited sidetone level).
March 1994
handbook, full pagewidth
handbook, full pagewidth
Low voltage versatile telephone transmission circuit
with dialler interface and transmit level dynamic limiting
Fig.14 Maximum output swing on line as a function of the DC voltage drop V
Fig.15 Alternative receiver arrangements: a) dynamic earpiece with an impedance less than 450 ; b) dynamic
R15 = 392 ; R16 = 56 ; or R15 = 0
earpiece with an impedance more than 450 ; c) magnetic earpiece with an impedance more than 450
resistor (1) may be connected to prevent distortion (inductive load); d) piezo-electric earpiece, resistor (2)
is required to increase the phase margin (stability with capacitive load).
11
5
4
V EE
QR
QR
(a)
V LN(p-p)
(V)
10
8
6
4
2
0
3
5
4
QR
QR
(b)
3.5
and R16 = 392
4
12
Receiving amplifier IR, QR , QR and GAR
The receiving amplifier has one input IR and two
complementary outputs, QR (non-inverting) and QR
(inverting). These outputs may be used for single-ended or
differential drive, depending on the type and sensitivity of
the earpiece used (see Fig.15). Gain from IR to QR is
typically 31 dB with R4 = 100 k , sufficient for
low-impedance magnetic or dynamic earpieces which are
suitable for single-ended drive. By using both outputs
(differential drive) the gain is increased by 6 dB.
Differential drive can be used when the earpiece
impedance exceeds 450
dynamic, magnetic or piezo-electric earpieces.
4.5
V LN -V SLPE (V)
5
4
56 = 448 .
QR
QR
(c)
5
MGR069
(1)
5.5
LN-SLPE
25
23
21
19
17
15
13
11
I line -I p
(mA)
with l
as with high-impedance
line
5
4
QR
QR
(d)
I
p
Product specification
as a parameter:
TEA1064A
(2)
MGR070