U4055B Datasheet, PDF (2/10 Pages) TEMIC Semiconductors – Low-Voltage Electronic Speech Circuit with Dialer Interface

U4055B/U4055B1
Pin Description
Pin Symbol
Function
1, 2 H₁ and H₂ The push-pull complementary
outputs of the receive amplifier.
W ^{Dynamic transducers with a}
minimum impedance of 100
can be directly driven by these
outputs.
3
GND Ground.
4
ST The output of the sidetone
cancellation signal, which
requires a balanced impedance
of 8–10 times the subscribers
line impedance to be connected
to Pin 13.
5
CK2 Input to the line output driver
amplifier. Transmit a.g.c. applied
to this stage.
6
CK1 The transmit pre-amp output
respective of the DTMF output
which is normally capacitively
coupled to Pin 5.
7, 8 MIC 1, Inputs of symmetrical
MIC 2 microphone amplifier with high
common mode rejection ratio.
9 DTMF IN The DTMF input has an internal
resistor connected to ground. It
provides the load resistor for the
emitter of a CMOS DTMF
generator. This input is only
active when MUTE (Pin 10) is
pulled high or MUTE is pulled
low.
10 MUTE or The MUTE input must be pulled
MUTE at least at 1.5 V (MUTE) or at
less than 0.5 V (MUTE) to mute
the MIC Amp. and Audio Amp.
and enable DTMF IN.
Pin Symbol
Function
11
V+ Regulated output voltage of
2.7 V for biasing a DTMF
generator activated by MUTE.
12 REC IN The receive amplifier input. The
receiving amplification is
regulated of an a.g.c.
13
V_L Positive supply voltage input to
the device. This input should be
connected to the positive output
of the polarity guard. The current
through this pin is modulated by
the transmit signal.
14
R_DC An external resistor (2 W) is
required from this pin to GND to
control the dc input impedance
of the circuit. It has a nominal
W value of 56 for low voltage
W operation. Values up to 100
may be used to increase the
available transmit output voltage
swing at the expense of low-
voltage operation.
15
V_I This internal voltage bias line
must be connected to V_L via an
external resistor, R_B, which
dominates the ac input imped-
ance of the circuit and should be
W 620 Ω for an 600 input
impedance or 910 Ω for a 900 Ω
input impedance.
16
R_AGC The range of transmit and
receive gain variations between
short and long loops may be
adjusted by connecting a resistor
R_EX1 from this pin to Pin 3
(GND). This pin can be left open
to set a.g.c. out of action.
2 (10)
TELEFUNKEN Semiconductors
Preliminary Information
Rev. A1, 06-May-96