E-LS1240A| Datasheet

E-LS1240A, LS1240

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LS1240
Electronic two-tone ringer
Features

Low current consumption, in order to allow the parallel operation of 4 devices Integrated rectifier bridge with zener diodes to protect against over voltages little external circuitry Tone and switching frequencies adjustable by external components Integrated voltage and current hysteresis Minidip

Description
LS1240 is a monolithic integrated circuit designed to replace the mechanical bell in telephone sets in connection with an electro-acoustical converter. It can drive directly a piezoceramic converter (buzzer) or a dynamic loudspeaker. The output current capability of LS1240 is higher than the one of a standard ringer. To drive a dynamic loudspeaker LS1240 can simply use a decoupling capacitor, thus eliminating the usual transformer. No current limitation is provided on the output stage of LS1240, so a minimum load DC of 50 is advised, in series with a proper capacitor. SO8 The two tone frequencies generated are switched by an internal oscillator in a fast sequence and are made audible across an output amplifier in the loudspeaker. Both tone frequencies and the switching frequency can be externally adjusted. The supply voltage is obtained from the AC ring signal and the circuit is designed so that noise on the line or variations of the ringing signal cannot affect correct operation of the device.

Pin connection (top view)

August 2006

Rev 2

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