L3240B1

L3240 ELETRONIC TWO-TONE RINGER . . . . . . 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 ADJUSTABLE BY EXTERNAL COMPONENTS INTEGRATED VOLTAGE AND CURRENT HYSTERESIS COMPLEMENTARY OUTPUT CONFIGURATION Minidip SO8 ORDERING NUMBERS : L3240B1 (Minidip) L3240D1 (SO8) DESCRIPTION L3240 is a monolithic integrated circuit designed to replace the mechanical bell in telephone sets, in connectionwith 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 sequenceand made audible across output amplifiers in the transducer ; 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 the correct operation of the devices. The output bridge configuration allows to use a high impedance transducer with acoustical results much better than in a single ended configuration. The two outputs can also be connected independently to different converters or actuators (acoustical, opto, logic). June 1993 PIN CONNECTION ( top view) 1/6 L3240 BLOCK DIAGRAM ABSOLUTE ...