L3240 Datasheet - STMicroelectronics

DESCRIPTION
L3240 is a monolithic integrated circuit designed to replace the mechanical bell in telephone sets, in connection with an electro acoustical converter.The device can drive either directly a piezo ceramic converter (buzzer) or a small loudspeaker. In this case a transformer is needed. The two tone frequencies generated are switched by an internal oscillator in a fast sequence and made audible across output amplifiers in the transducer; both tone frequencies and the switching frequency can be externally adjusted.

. LOW CURRENT CONSUMPTION, IN ORDER TO ALLOW THE PARALLEL OPERATION OF 4 DEVICES
. INTEGRATED RECTIFIER BRIDGE WITH ZENER DIODES TO PROTECT AGAINST OVERVOLTAGES
. LITTLE EXTERNAL CIRCUITRY
. TONE AND SWITCHING FREQUENCIES AD JUSTABLE BY EXTERNAL COMPONENTS
. INTEGRATED VOLTAGE AND CURRENT HYSTERESIS
. COMPLEMENTARY OUTPUT CONFIGURATION