GL6965 datasheet(13/23 Pages) HYNIX

13 / 23 page

GL6965

Description Functions

1. Line voltage increasing circuit (up)

The voltage of VL,VCC or VREF can be increased by connecting UP terminal to GND directly or

through the resistance.

The internal equivalent circuit is as shown in the figure.

(1) The voltage increased most up to about 1.5V in VL when UP terminal is directly connected to

GND. when the resistance is inserted the voltage increases according to the resistance value.

(See graph)

(2) In case of usage with MUTE terminal connected, the line voltage can be increased only at

muting.

(3) Avoid impressing the voltage over VCC or under GND.

(4) When not in use, make the circuit opened or connected to VCC.

Internal equivalent circuit

2. Side tone protection circuit (Balancing circuit)

The time constant (hereafter referred to as BN constant) of the side tone protection circuit in the

example of application circuit is adjusted nearly to 0.4

φ 7dB. Since the side tone characteristic

varies according to this BN time constant, adjust the time constant confirming to the function of the

telephone set.

EXAMPLE OF BN TIME CONSTANT

In case of 0.5

φ 7dB is determined

to be the center.

PIN20 (VCC)

PIN20 (UP)

10k

5 k

1.5

lUP

0.015

µF

10 k

Ω

2.0 k§ Ù

6.2 k§ Ù

GL6965 Datasheet(PDF) 13 Page - Hynix Semiconductor