TEA1093 Просмотр технического описания (PDF) - Philips Electronics

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TEA1093

Hands-free IC

Philips Electronics 

Philips Semiconductors

Hands-free IC

Product specification

TEA1093

handbook, full pagewidth

RGAR 5 GAR

CLSP1

from voltage

stabilizer

6 LSP1

CDLC 1 DLC/MUTER

DYNAMIC

LIMITER

to

to to/from envelope

logic voice switch detector

VI

IV

RIN1 2

RIN2 3

from

TEA106X

4 LSP2

−1

Fig.7 Loudspeaker channel.

VOLUME VOL 11

CONTROL

RVOL

MGD222

Loudspeaker channel

LOUDSPEAKER AMPLIFIER: PINS RIN1, RIN2, GAR, LSP1

AND LSP2

The TEA1093 has symmetrical inputs for the loudspeaker

amplifier with an input resistance of 40 kΩ between RIN1

and RIN2 (2 × 20 kΩ). The input stage can accommodate

signals up to 390 mV (RMS) at room temperature for 2% of

total harmonic distortion (THD). The gain of the input stage

varies according to the mode of the TEA1093. In the

receive mode, the gain is at its maximum; in the transmit

mode, it is at its minimum and in the idle mode, it is halfway

between maximum and minimum. Switch-over from one

mode to the other is smooth and click-free. The rail-to-rail

output stage is designed to power a loudspeaker which is

connected as a single-ended load (between LSP1 and

GND) or as a bridge-tied load (between LSP1 and LSP2).

In the receive mode, the overall gain of the loudspeaker

amplifier can be adjusted from 3 dB up to 39 dB to suit

specific application requirements. The gain from RIN1 or

RIN2 to LSP1 is proportional to the value of RGAR and

equals 18 dB with RGAR = 66.5 kΩ. The second output

LSP2 is in opposite phase with LSP1. Therefore, in the

basic application, the gain between RIN1-RIN2 to

LSP1-LSP2 equals 24 dB typical with RGAR = 66.5 kΩ.

A capacitor connected in parallel with RGAR can be used to

provide a first-order low-pass filter.

VOLUME CONTROL: PIN VOL

The loudspeaker amplifier gain can be adjusted with the

potentiometer RVOL. A linear potentiometer can be used to

obtain logarithmic control of the gain at the loudspeaker

amplifier. Each 950 Ω increase of RVOL results in a gain

loss of 3 dB. The maximum gain reduction with the volume

control is internally limited to the switching range.

DYNAMIC LIMITER: PIN DLC/MUTER

The dynamic limiter of the TEA1093 prevents clipping of

the loudspeaker output stages and protects the operation

of the circuit when the supply condition falls below a

certain level.

Hard clipping of the loudspeaker output stages is

prevented by rapidly reducing the gain when the output

stages start to saturate. The time in which gain reduction

is effected (clipping attack time) is approximately a few

milliseconds. The circuit stays in the reduced gain mode

until the peaks of the loudspeaker signals no longer cause

saturation. The gain of the loudspeaker amplifier then

returns to its normal value within the clipping release time

(typical 250 ms). Both attack and release times are

proportional to the value of the capacitor CDLC. The total

harmonic distortion of the loudspeaker output stages, in

reduced gain mode, stays below 5% up to 10 dB

(minimum) of input voltage overdrive [providing VRIN is

below 390 mV (RMS)].

1996 Feb 09

9

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