LC73720

The LC73720 is designed as one kind of DTMF / output pulse dial CMOS LSI for pushbutton telephones. It contains 16-digit 24-telephone number one-touch autodialing memory, 21-telephone number abbreviated dialing memory (common with one-touch dialing), and 63-digit redialing memory, as well as on-hook dialing, and privacy functions on a single chip.

Features of the LC73720 are:(1)uses CMOS processes that can work directly with telephone lines;(2)single-contact keyoards can be used;(3)the built-in oscillator can use color television crystal oscillators and ceramic resonators;(4)the use of a high-precision DTMF signal frequency generation circuit (+/-0.1%) make it easy to distinguish ceramic resonators;(5)memory registration can specify on-hook or off-hook;(6)mode changes, pauses, and hooking data can be written into dialing memory;(7)this chip is equipped with a 63-digit redialing memory;(8)for mode switching a pause (2.0 seconds) is inserted automatically;(9)after the flash operation, a pause (1.0 second) is inserted automatically;(10)mode changes are one direction, from pulse mode to tone mode;(11)DTMF mode enerates 12 types of signals.

The absolute maximum ratings of the LC73720 can be summarized as:(1)maximum supply voltage: -0.3 to +6.5 V;(2)maximum input voltage: -0.3 to VDD+0.3 V;(3)allowable power dissipation: 250 mW;(4)operating temperature: -30 to +70 ;(5)storage temperature: -40 to +125 ;(6)maximum output voltage: -0.3 to VDD+0.3 V. If you want to know more information such as the electrical characteristics about the LC73720, please download the datasheet in www.seekic.com or www.chinaicmart.com.