TONE_DIALING_TELEPHONE

Published:2009/7/7 21:11:00 Author:May | From:SeekIC

This circuit shows the TP5700 directly interfacing to a low-voltage DTMF generator.VREG1 supplies the necessary 2-V minimum bias to enable the TP5380 to sense key closures and pull its mute output high.VREG1 then switches to a 3-V regulated output to sustain the tone dialer during tone generation. The TP5700 DTMF input incorporates the necessary load resistor to V- and provides gain, plus AGC action, to compensate for loop length. A muted tone level is heard in the receiver. For DTMF generators with a higher output level than the TP5380, a resistive potentiometer should be added to reduce the level at the speech circuit DTMF input.



Reprinted Url Of This Article:
http://www.seekic.com/circuit_diagram/Electrical_Equipment_Circuit/Telephone-Related_Circuit/TONE_DIALING_TELEPHONE.html

Print this Page | Comments | Reading(3)