ELETRONIC TWO-TONE RINGER
Description
L3240
ELETRONIC TWO-TONE RINGER
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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 MAXIMUM RATINGS
Symbol VAB VAB DC Top Tstg Parameter Calling Voltage (f = 50 Hz) Continuous Calling Voltage (f = 50 Hz) 5s N/10s OFF Supply Current Operating Temperature Storage and Junction Temperature Value 120 200 30 – 20, + 70 – 65, + 150 Unit VRMS VRMS mA o C o C
THERMAL DATA
Symbol Rth j-amb Parameter Thermal Resistance Junction-ambient Max.
Value 100 Unit
o
C/W
ELECTRICAL CHARACTERISTICS (Tamb = 25oC ; VS = applied between pins 7-2 ;otherwise specified)
Symbol Vs IB VON VOFF RD VOUT IO...
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