TEA1066T Philips Semiconductors (Acquired by NXP), TEA1066T Datasheet - Page 5

• Manufacturer Part Number: TEA1066T
• Description: Versatile Telephone Transmission Circuit With Dialer Interface
• Manufacturer: Philips Semiconductors (Acquired by NXP)

Philips Semiconductors
The voltage regulator adjusts the average voltage on
LN to:
or
where V
compensated reference voltage of 4.2 V and R9 is an
external resistor connected between SLPE and V
The preferred value for R9 is 20
R9 will also affect microphone gain, DTMF gain, gain
control characteristics, side-tone level and the maximum
output swing on LN.
Under normal conditions, when I
the static behaviour of the circuit is that of a 4.2 V regulator
diode with an internal resistance equal to that of R9. In the
audio frequency range, the dynamic impedance is largely
determined by R1 (see Fig.3).
The internal reference voltage can be adjusted by means
of an external resistor R
between LN and REG (pins 1 and 18), will decrease the
internal reference voltage; when connected between REG
and SLPE (pins 18 and 20) it will increase the internal
reference voltage.
Current I
circuits, depends on external components and on the line
current. Figure 8 shows this current for V
1996 Apr 04
handbook, halfpage
V
V
Versatile telephone transmission circuit
with dialler interface
R
L
LN
LN
eq
p
= V
= V
17.5 k
C3
ref
p
, available from V
ref
ref
V
is an internally generated temperature
Fig.3 Equivalent impedance circuit.
R9
LN
EE
+ I
+ (I
SLPE
R
line
p
I
CC
R9
L eq
R9
20
VA
V ref
. This resistor, connected
0.5
CC
for supplying peripheral
SLPE
10
R p
REG
C3
4.7 F
Changing the value of
3
>> I
A
CC
I
CC
p
MBA454
)
R1
V CC
C1
100 F
+ 0.5 mA + I
> 2.2 V
R9
EE
.
p
,
5
and > 3 V, this being the minimum supply voltage for most
CMOS circuits, including voltage drop for an enable diode.
If MUTE is LOW, the available current is further reduced
when the receiving amplifier is driven.
Microphone inputs MICL+, MICH+, MICL and MICH
and amplification adjustment connections GAS1 and
GAS2
The TEA1066T has symmetrical microphone inputs.
The MICL+ and MICL inputs are intended for
low-sensitivity, low-impedance dynamic or magnetic
microphones. The input impedance is 8.2 k (2
and its voltage gain is typically 52 dB. The MICH+ and
MICH inputs are intended for a piezoelectric microphone
or an electret microphone with a built-in FET source
follower. Its input impedance is 40.8 k (2
its voltage gain is typical 38 dB.
The arrangements with the microphone types mentioned
are shown in Fig.9.
The gain of the microphone amplifier in both types can be
adjusted over a range of 8 dB to suit the sensitivity of the
transducer used. The gain is proportional to external
resistor R7 connected between GAS1 and GAS2.
An external capacitor C6 of 100 pF between GAS1 and
SLPE is required to ensure stability. A larger value may be
chosen to obtain a first-order low-pass filter. The cut-off
frequency corresponds with the time constant R7
Mute input MUTE
A HIGH level at MUTE enables the DTMF input and
inhibits the microphone inputs and the receiving amplifier;
a LOW level or an open circuit has the reverse effect.
Switching the mute input will cause negligible clicks at the
earpiece outputs and on the line.
Dual-tone multi frequency input DTMF
When the DTMF input is enabled, dialling tones may be
sent onto the line. The voltage gain from DTMF to LN is
typically 25.5 dB and varies with R7 in the same way as
the gain of the microphone amplifier. The signalling tones
can be heard in the earpiece at a low level (confidence
tone).
Receiving amplifier: IR, QR+, QR and GAR
The receiving amplifier has one input IR and two
complementary outputs, a non-inverting output QR+ and
an inverting output QR .
Product specification
TEA1066T
20.4 k ) and
4.1 k )
C6.