U4050B Datasheet, PDF (3/18 Pages) TEMIC Semiconductors – Speech Circuit with Line-Powered Loudspeaker Amplifier

Pin Description
RECO2 ₁
28 ^IREF
GR
2
27 ^AGA
RECO1 3
26 GSA
ST
4
25 PD
CLIM 5
24 VC
CK
6
23 VL
MICO 7
22 GND
DTMF 8
21 ^SAO
GS
9
20 VD
MIC1 10
19 RDC
MIC2 11
18 SWAMP
LEVSQ 12
17 ^CLISA
CSQ 13
16 MUTE
VM
14
15 TIN
14052
Figure 3. Pinning S028
Pin Symbol
Function
1
RECO2, Symmetrical outputs of receiving
3
RECO1 amplifier
2
GR A resistor connected from this pin to
V_M (AC coupled) sets the receiving
amplification at the circuit
4
ST
Input of sidetone amplifier
5
CLIM Time constant of anticlipping in trans-
mit patch
6
CK Input of receiving path
7
MICO Output of microphone preamplifier
8
DTMF Input for DTMF signals (ac coupled).
In Mute condition a small portion of
the signal at this pin is monitored to
the receiver output.
9
GS
A resistor from this pin to V_M sets the
amplification of microphone and
DTMF signals.
10
MIC1 Inverting input of microphone ampli-
fier
U4050B
Pin Symbol
Function
11
MIC2 Non-inverting input of microphone
amplifier
12
LEVSQ Input for setting the switching level of
the squelch circuit
13
CSQ Time constant of the squelch function
14
VM Reference node for microphone, ear-
phone and loudspeaker amplifier.
Supply for electret microphone set to
V_D/2.
15
TIN Input of intermediate transmit stage
16
MUTE Active high input to switch the circuit
into DTMF condition.
17
CLISA Time constant of anticlipping of
speaker amplifier.
18 SWAMP 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
19
RDC 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.
20
VD Unregulated supply voltage for pe-
ripheral circuits (dialers, microproces-
sors, etc.). Output current capability
and output voltage increase with line
current.
21
SAO Output of loudspeaker amplifier.
22
GND Reference point for DC and AC out-
put signals
23
VL Line voltage
24
VC 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.
25
PD Active high input for reducing the
current consumption of the circuit.
Simultaneously V_L is shorted by an
internal switch.
26
GSA Current input for setting the gain of
the speaker amplifier
27
AGA 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.
28
IREF Internal reference current generation
Rev. A2, 05-Mar-98
3 (18)