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226

Communication ICs

Speech network for telephones

BA6569AS / BA6569AFP

The BA6569AS and BA6569AFP are speech networks which possesses the basic functions required for handset com-

munications. In addition to amplifying signals from a transmitter and sending them to a telephone line, they also amplify

only reception signals from a telephone line and drive the receiver. In addition to a function which compensates for fluc-

tuation in the transmission and reception volume caused by the length of the telephone line (AGC), they are also

equipped with a manual PAD function in order to accommodate PBX.

F

Applications

Telephones and telephone equipment

F

Features

1) Basic speech network functions built in.

2) Single output pin of reception pre-amplifier is sepa-

rate.

3) Single input pin of reception pre-amplifier is sepa-

rate, enabling mixing of input.

4) Input to microphone pre-amplifier is balanced and of-

fers high resistance to in-line noise.

5) Input pin of MF pre-amplifier enables mixing of input.

6) Manual pad pin included.

7) Pre-amplifiers for reception, microphone, and MF

employ AGC based on telephone line current.

8) AC impedance can be raised by altering the posi-

tive feedback. This enables configuration of power

supply circuits for microcomputers and other ap-

plications using only a single resistor.

9) A BTL circuit is used for reception output, and the

wide dynamic range enables both dynamic and ce-

ramic receivers to be accommodated.

10) Few external attachments are required.

11)

22-pin SDIP and 24-pin HSOP packages available.

F

Absolute maximum ratings (Ta = 25

_

C)

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227

Communication ICs

BA6569AS / BA6569AFP

F

Block diagram

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228

Communication ICs

BA6569AS / BA6569AFP

F

Electrical characteristics (unless otherwise noted, Ta = 25

_

C, f = 1kHz, BPF = 400Hz to 30kHz)

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229

Communication ICs

BA6569AS / BA6569AFP

F

Electrical characteristic curves

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230

Communication ICs

BA6569AS / BA6569AFP

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231

Communication ICs

BA6569AS / BA6569AFP

F

Measurement circuits

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232

Communication ICs

BA6569AS / BA6569AFP

F

Circuit operation

The BA6569AS and BA6569AFP carry out the following

basic operations.

(1)

Handset talk and receive

Voice signals received from a telephone line are output

to a handset speaker. Voice signals from the handset mi-

crophone are also output to the telephone line.

(2)

DTMF send and key tone input

The BA6569AS and BA6569AFP have a mute switch

which can be switched between a “handset send and re-

ceive” mode and a “DTMF send and key tone input”

mode by an external logic signal. In the “DTMF send and

key tone input” mode, it transmits DTMF signals from the

dial pad to the telephone line, and key tones to the hand-

set receiver.

(3)

AGC

Gain is adjusted steplessly in response to the size of cur-

rent from the telephone line. When there is a large cur-

rent (a short distance is involved), the gain is lowered.

The gain volume can also be adjusted by changing the

value of the resistor connected to the AGC pin.

(4)

Manual pad

In order to accommodate situations such as a PBX,

where there is little current but a short distance is in-

volved, the gain can be lowered by a constant volume re-

gardless of the current value. Fluctuation in the amount

of gain can be adjusted by changing the value connected

to the MPAD pin.

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233

Communication ICs

BA6569AS / BA6569AFP

F

Pin descriptions

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234

Communication ICs

BA6569AS / BA6569AFP

F

Operation notes

The maximum power dissipation for the BA6569AS is

1100mW, and for the BA6569AFP, the maximum power

dissipation is 1200mW (when mounted on 90mm 

 

50mm 

 

 1.6mm glass epoxy boards, however, fins

should be soldered to the foil pattern). Since the maxi-

mum power dissipation varies with temperature, the

product of the applied voltage VL and the total current

drawn by the IC, after factoring in the temperature,

should not exceed the maximum dissipation.

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235

Communication ICs

BA6569AS / BA6569AFP

F

Application example

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236

Communication ICs

BA6569AS / BA6569AFP

F

Application board pattern

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F

External dimensions (Units: mm)

237

Communication ICs

BA6569AS / BA6569AFP

F

Application board component layout