U4037B Datasheet, PDF (3/6 Pages) TEMIC Semiconductors – LOW VOLTAGE SPEECH CIRCUIT WITH TONE RINGER INTERFACE

Pin Description
Pin Symbol
Function
OUT Buzzer output
MELI Melody input
RECO1 Output of the receiver amplifier
RECO2 Suitable for dynamic or piezoelec-
tronic transducers
GND Ground
ST The output of the sidetone can-
cellation signal, which requires a
balanced impedance of 8 to
10 times the subscribers line
impedance to be connected to
Pin V_L.
TIN Input to the line output driver
amplifier, transmit a.g.c. applied
to this stage
MICO Transmit pre-amplifier output
MIC 1,
MIC 2
Inputs of symmetrical microphone
amplifier with high common mode
rejection ratio
V_DD Regulated output voltage of for
biasing the MCU
RECIN Receive amplifier input
The receiving amplification is
regulated by an a.g.c.
V_L Positive supply voltage input to
the device
The current through this pin is
modulated by the transmit signal.
U4037B
Pin Symbol
Function
SWAMP
An external resistor (1 W) is
required from this pin to GND to
control the dc input impedance of
the circuit. It has a nominal value
W of 56 for low voltage operation.
VOI1 Volume adjustment of ringer and
VOI2 earphone amplifier
RFO Output for ringing frequency
detection
V_I This internal voltage bias line
must be connected to V_L via an
external resistor, R_B, which domi-
nates the ac input impedance of
W ^{the circuit and should be 620 Ω}
for an 600 input impedance or
910 Ω for a 900 Ω input
impedance.
R_AGC
The range of transmit and receive
gain variations between short and
long loops may be adjusted by
connecting a resistor R_AGC from
this pin to (GND). This pin can be
left open to set a.g.c. out of action.
DTMF DTMF input
MUTE Control input for DTMF operation
VB Ringer supply
RDC Input for setting the DC
characteristic
TELEFUNKEN Semiconductors
3 (6)
Rev. A1, 08-Oct-96
Preliminary Information