TEA1096 查看數據表（PDF） - Philips Electronics

零件编号

产品描述 (功能)

生产厂家

TEA1096

Speech and listening-in IC

Philips Electronics 

Philips Semiconductors

Speech and listening-in IC

Product Specification

TEA1096; TEA1096A

Fig.10 Dynamic limiter of the microphone channel.

Receiving amplifier: pins LN, GAR, QRP and QRM

The receiver gain is defined between the line connection

LN and the earpiece complementary outputs QRP

(non-inverting) and QRM (inverting). With RGAR equal to

90.9 kΩ the gain from LN to QRP is −2.5 dB. The outputs

may be used to connect a dynamic, magnetic or

piezoelectric earpiece. When the earpiece impedance

exceeds 450 Ω, differential drive (BTL connection) can be

used. As both outputs are in opposite phase, the gain from

LN to QRP or QRM is 3.5 dB.

By means of the RGAR resistor, the gain of the receiving

amplifier can be adjusted to suit the sensitivity of the

transducer which is used. The permitted range is between

−14 dB and +6 dB for single-ended drive (SE), and

between −8 dB and +12 dB for bridge-tied load (BTL)

drive.

Two external capacitors, CGAR (100 pF) and CGARS (1 nF),

ensure stability. The CGAR capacitor is also used to obtain

a first-order low-pass filter. The cut-off frequency

(corresponding to the time constant RGAR × CGAR) can be

adjusted by the CGAR capacitor, but the relationship

CGARS = CGAR × 10 must be maintained.

During DTMF dialling, the dialling tones can be heard in

the earpiece at a very low level. This is called confidence

tone.

Automatic gain control: pin AGC

Automatic compensation of line-loss is obtained by

connecting a resistor RAGC between pin LN and pin AGC.

This automatic gain control changes the gain of the

microphone and receiving amplifiers in accordance with

the DC line current.

The control range is 6 dB; This corresponds to a 5 km line

of 0.5 mm diameter copper twisted-pair cable:

DC resistance = 176 Ω /km

average attenuation = 1.2 dB/km.

The value of RAGC must be chosen with reference to the

exchange supply voltage and its feeding bridge resistance

and has no influence on the ratio (Istart/Istop) which remains

constant. Figure11 illustrates the gain attenuation when

RAGC = 100 kΩ. If automatic line-loss compensation is not

required, the AGC pin can be left open circuit, the

amplifiers then give their maximum gain and the double

sidetone principle is no longer active. Only one network is

used. Pins BAL1 and BAL2 must then be short-circuited

together.

November 1994

12

Share Link: