E-LS1240AD1 Datasheet - STMicroelectronics

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 Ω is advised, in series with a proper capacitor.

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