KA8601C datasheet(8/10 Pages) SAMSUNG

8 / 10 page

KA8601C

SPEAKER PHONE WITH SPEECH NETWORK

VOLUME CONTROL

The volume control can only be applied in the receive mode. If the voltage of the VC mode is the same as the VB, the

receive attenuator gain is maximized and the transmit gain is minimized. At the same time, if the VC mode voltage is

less than the VB, the receive attenuator gain is reduced.

Fig. 5

VOICE DETECTION FUNCTION

The voice detection function compares the microphone amplifier output level with the outside audio amplifier level

and the transmit attenuator output level with the receive attenuator input level, after which they are inputted into the

control box. The block diagram of the voice detection function is as follows:

Fig. 6

It is useful to use a background noise monitor when high background noise occurs. When the input signals to the

background noise monitor are increased, voltage for the PDRX (PDTX) mode is stably increased. The increase time

is determined by 100K

Ω and 47µF.

ATTENUATOR CONTROL BOX

In figure 6, each signal coming into the log amplifier is amplified and then inputted into the comparator (C1, C2). The

comparator compares the amplified signal levels, after which they are inputted into the attenuator control box. The

attenuator control box processes these signals (CO1, CO2, CO3, CO4) as logic signals, and which are put into one

of the following modes:

KA8601C

VOLUME

DETI

RX 1

DETI

TX 1

Log Amp

DETORX 1

DETOTX 1

Comparator

PDRX

Background

Noise Monitor

CO1

CO2

Attenuator Control Box

DETI TX

DETI

RX 1

Log Amp

DETOTX 1

Comparator

PDTX

CO4

CO3

KA8601C Datasheet(PDF) 8 Page - Samsung semiconductor

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