U4050B
Pin Description
RECO2
GR
RECO1
ST
CLIM
CK
MICO
DTMF
GS
MIC1
MIC2
LEVSQ
CSQ
VM
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28 IREF
27 AGA
Pin
11
12
Symbol
MIC2
LEVSQ
CSQ
VM
26 GSA
25 PD
24 VC
23 VL
22 GND
21 SAO
20 VD
19
RDC
13
14
15
16
17
18
TIN
MUTE
CLISA
SWAMP
18 SWAMP
17
16
15
CLISA
MUTE
TIN
14052
19
RDC
20
VD
Figure 3. Pinning S028
Pin
1
3
2
Symbol
RECO2,
RECO1
GR
4
5
6
7
8
ST
CLIM
CK
MICO
DTMF
9
GS
10
MIC1
Function
Symmetrical outputs of receiving
amplifier
A resistor connected from this pin to
V
M
(AC coupled) sets the receiving
amplification at the circuit
Input of sidetone amplifier
Time constant of anticlipping in trans-
mit patch
Input of receiving path
Output of microphone preamplifier
Input for DTMF signals (ac coupled).
In Mute condition a small portion of
the signal at this pin is monitored to
the receiver output.
A resistor from this pin to V
M
sets the
amplification of microphone and
DTMF signals.
Inverting input of microphone ampli-
fier
21
22
23
24
SAO
GND
VL
VC
25
PD
26
27
GSA
AGA
28
IREF
Function
Non-inverting input of microphone
amplifier
Input for setting the switching level of
the squelch circuit
Time constant of the squelch function
Reference node for microphone, ear-
phone and loudspeaker amplifier.
Supply for electret microphone set to
V
D
/2.
Input of intermediate transmit stage
Active high input to switch the circuit
into DTMF condition.
Time constant of anticlipping of
speaker amplifier.
A resistor connected from this pin to
ground converts the excess line cur-
rent into heat in order to prevent the
IC from thermal destruction at high
line currents
A small resistor connected from this
pin to V
L
sets the slope of the charac-
teristic and also affects the line length
equalization characteristics and the
line current at which the loudspeaker
amplifier is switched on.
Unregulated supply voltage for pe-
ripheral circuits (dialers, microproces-
sors, etc.). Output current capability
and output voltage increase with line
current.
Output of loudspeaker amplifier.
Reference point for DC and AC out-
put signals
Line voltage
The internal equivalent inductance of
the circuit is proportional to the value
of the capacitor at this pin. A resistor
connected to ground may be used to
reduce the line voltage.
Active high input for reducing the
current consumption of the circuit.
Simultaneously V
L
is shorted by an
internal switch.
Current input for setting the gain of
the speaker amplifier
Automatic gain adjustment with line
current. A resistor connected from this
pin to V
L
sets the starting point.
Maximum gain change is 6 dB.
Internal reference current generation
Rev. A2, 05-Mar-98
3 (18)
TEMIC [ TEMIC SEMICONDUCTORS ]
