TEA1064BT/C1 Просмотр технического описания (PDF) - Philips Electronics

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TEA1064BT/C1

Low voltage versatile telephone transmission circuit with dialler interface and transmit level dynamic limiting

Philips Electronics 

Philips Semiconductors

Low voltage versatile telephone transmission circuit

with dialler interface and transmit level dynamic limiting

Product specification

TEA1064B

Microphone inputs MIC+ and MIC− and gain pins

GAS1 and GAS2

The TEA1064B has symmetrical microphone inputs, its

input impedance is 64 kΩ (2 x 32 kΩ) and its voltage

amplification is typically 52 dB with R7 = 68 kΩ. Either

dynamic, magnetic or piezo-electric microphones can be

used, or an electret microphone with a built-in FET buffer.

Arrangements for the microphone types are shown in

Fig.10.

The gain of the microphone amplifier is proportional to

external resistor R7 connected between GAS1 and GAS2

and with this it can be adjusted between 44 dB and

52 dB to suit the sensitivity of the transducer.

An external 100 pF capacitor (C6) is required between

GAS1 and SLPE to ensure stability. A larger value of C6

may be chosen to obtain a first-order low-pass filter with a

cut-off frequency corresponding to the time constant

R7 x C6.

handbook, full pagewidth

MIC+

9

(1)

MIC−

8

(a)

VCC

MIC−

16

8

MIC+

9

11

VEE1

(b)

MIC+

9

MIC−

8

MBA439

(c)

Resistor (1) may be connected to reduce the terminating impedance, or for sensitive types a resistive attenuator

can be used to prevent overloading the microphone inputs.

Fig.10 Microphone arrangements (a) magnetic or dynamic microphone (b) electret microphone (c) piezo-electric

microphone currents.

March 1994

10

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