TEA1113 查看數據表（PDF） - Philips Electronics

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TEA1113

Low voltage versatile telephone transmission circuit with dialler interface

Philips Electronics 

Philips Semiconductors

Low voltage versatile telephone

transmission circuit with dialler interface

Product specification

TEA1113

on the line signal remain below the threshold level.

The microphone gain then returns to its nominal value after

a time determined by the capacitor CDLS (release time).

The maximum output swing on the line depends on the DC

voltage setting (Vref). The internal threshold level is

automatically adapted.

A LOW level on pin DLS/MMUTE inhibits the microphone

inputs MIC+ and MIC− without affecting the DTMF and

receiving inputs. Removing the LOW level from pin

DLS/MMUTE provides the normal function of the

microphone amplifier after a short time which is

determined by capacitor CDLS. With the value of the

capacitor at 470 nF, the release time is in the order of a

few tenths of a millisecond. The microphone mute function

can be realized by a simple switch as illustrated in Fig.9.

Receiving amplifier (pins IR, GAR and QR)

The receiving amplifier has one input (IR) and one output

(QR). The input impedance between pin IR and pin VEE is

20 kΩ. The voltage gain from pin IR to pin QR is fixed to

31.3 dB (typ). The gain can be decreased by connecting

an external resistor RGAR between pins GAR and QR; the

adjustment range is 12 dB. Two external capacitors CGAR

(connected between GAR and QR) and CGARS (connected

between GAR and VEE) ensure stability. The CGAR

capacitor provides a first-order low-pass filter. The cut-off

frequency corresponds to the time constant

CGAR × (RGARint // RGAR). RGARint is the internal resistor

which sets the gain with a typical value of 100 kΩ.

The relationship CGARS = 10 × CGAR must be fulfilled to

ensure stability.

The output voltage of the receiving amplifier is specified for

continuous wave drive. The maximum output swing

depends on the DC line voltage, the RCC resistor, the ICC

current consumption of the circuit, the Ip current

consumption of the peripheral circuits and the load

impedance.

Automatic gain control is provided on this amplifier for line

loss compensation.

Automatic gain control (pin AGC)

The TEA1113 performs automatic line loss compensation.

The automatic gain control varies the gain of the

microphone amplifier and the gain of the receiving

amplifier in accordance with the DC line current.

The control range is 5.8 dB (which corresponds

approximately to a line length of 5 km for a 0.5 mm

diameter twisted-pair copper cable with a DC resistance of

176 Ω/km and an average attenuation of 1.2 dB/km).

The IC can be used with different configurations of feeding

bridge (supply voltage and bridge resistance) by

connecting an external resistor RAGC between pins AGC

and VEE. This resistor enables the Istart and Istop line

currents to be increased (the ratio between Istart and Istop is

not affected by the resistor). The AGC function is disabled

when pin AGC is left open-circuit.

Mute function (pin MUTE)

The mute function performs the switching between the

speech mode and the dialling mode. When MUTE is LOW

or open-circuit, the DTMF input is enabled and the

microphone and receiving amplifiers inputs are disabled.

When MUTE is HIGH, the microphone and receiving

amplifiers inputs are enabled while the DTMF input is

disabled.

DTMF amplifier (pin DTMF)

When the DTMF amplifier is enabled, dialling tones may

be sent on line. These tones can be heard in the earpiece

at a low level (confidence tone).

The TEA1113 has an asymmetrical DTMF input. The input

impedance between DTMF and VEE is 20 kΩ. The voltage

gain from pin DTMF to pin LN is 25.4 dB. When the

resistor RGAS is connected, to decrease the microphone

gain, the DTMF gain varies in the same way (the DTMF

gain is 26.4 dB lower than the microphone gain with no

AGC control).

The automatic gain control has no effect on the DTMF

amplifier.

Sidetone suppression

The TEA1113 anti-sidetone network comprising

RCC // Zline, Rast1, Rast2, Rast3, RSLPE and Zbal (see Fig.10)

suppresses the transmitted signal in the earpiece.

Maximum compensation is obtained when the following

conditions are fulfilled:

RSLPE × Rast1 = RCC × (Rast2 + Rast3)

k = -(---R-----a--s---t-(-2--R--×--a---s(---tR-1---a-×--s---tR-3---S-+---L--R-P---E-S--)-L---P---E---)----)--

Zbal = k × Zline

The scale factor k is chosen to meet the compatibility with

a standard capacitor from the E6 or E12 range for Zbal.

1997 Mar 27

7

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