
L3240
June1993
ELETRONIC TWO-TONE RINGER
.
LOW CURRENT CONSUMPTION, IN ORDER
TOALLOWTHEPARALLELOPERATIONOF4
DEVICES
.
INTEGRATED
ZENER DIODES TO PROTECT AGAINST
OVERVOLTAGES
.
LITTLEEXTERNAL CIRCUITRY
.
TONE AND SWITCHING FREQUENCIES AD-
JUSTABLEBY EXTERNAL COMPONENTS
.
INTEGRATED
HYSTERESIS
.
COMPLEMENTARY OUTPUT CONFIGURA-
TION
RECTIFIER BRIDGE
WITH
VOLTAGE AND CURRENT
DESCRIPTION
L3240is a monolithic integratedcircuit designed to
replace the mechanical bell in telephone sets, in
connectionwithanelectroacousticalconverter.The
devicecandriveeitherdirectlyapiezoceramiccon-
verter (buzzer)or a smallloudspeaker.In this case
a transformer is needed.The two tonefrequencies
generatedareswitched by aninternaloscillatorin a
fast sequenceandmade audibleacrossoutputam-
plifiers inthetransducer;bothtonefrequenciesand
the switching frequencycan be externallyadjusted.
Thesupplyvoltageis obtainedfromtheAC ringsig-
nal and the circuit is designedso thatnoise on the
line or variationsof the ringingsignal cannotaffect
the correct operationof the devices.
Theoutputbridge configurationallows touseahigh
impedancetransducerwith acousticalresults much
betterthanin a singleended configuration.
The two outputs can also be connected inde-
pendently to
different
tors (acoustical, opto,logic).
converters
or
actua-
PIN CONNECTION
( top view)
Minidip
SO8
ORDERINGNUMBERS :
L3240B1 (Minidip)
L3240D1 (SO8)
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