U4082BL-S28-R datasheet(10/13 Pages) UTC

10 / 13 page

UNISONIC TECHNOLOGIES CO., LTD

U4082B

LINEAR INTEGRATED CIRCUIT

UNISONICTECHNOLOGIESCO.,LTD

10 of 13

www.unisonic.com.tw

QW-R108-020.A

FUNCTIONAL DESCRIPTION(Cont.)

AGC

The AGC circuit only affects the circuit under such situation: when the circuit is in the receive mode, and when

VCC is less than 3.5v. As while as VCC falls below 3.5 volts, the transmit path attenuation changes so that the sum of

the transmit and receive gains remains constant.

ATTENUATOR CONTROL BLOCK

This block has the seven:

* C1: The output of the comparator operated by RLO2 and TLO2 (here means in microphone/ speaker side).

* C2: The output of the comparator operated by RLO1 and TLO1 (here means Tip/ Ring side).

* C3: The output of the transmit background noise monitor.

* C4: The output of the receive background noise monitor.

* Volume control

* Dial tone detector

* AGC circuit

The C1~C4 effect is as follows:

INPUTS

OUTPUT

Transmit Mode

Fast Idle Mode

Receive Mode

Slow Idle Mode

Switching to the full transmit or receive from any other mode is at the fast rate (~30 ms).

X :Don’t care

Y :C3,C4 are not both 0

U4082BL-S28-R Datasheet(PDF) 10 Page - Unisonic Technologies