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LS1241
ELECTRONIC TWO - TONE RINGER
I ..
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LS1241
Electronic Two
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LS1241
ELECTRONIC TWO - TONE RINGER
I LOW CURRENT CONSUMPTION, IN ORDER
TO ALLOW THE PARALLEL OPERATION OF A
DEVICE
I INTEGRATED RECTIFIER BRIDGE WITH
ZENER DIODES TO PROTECT AGAINST
OVER VOLTAGES
I LITTLE EXTERNAL CIRCUITRY
I TONE AND SWITCHING FREQUENCIES AD-
JUSTABLE BY EXTERNAL COMPONENTS
I INTEGRATED VOLTAGE AND CURRENT
HYSTERESIS
DESCRIPTION
LS1241 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 con-
verter (buzzer) or a small loudspeaker. In this case
a transformer is needed. The two tone frequencies
generated are switched by an output amplifier in the
loudspeaker ; both tone frequencies and the switch-
ing frequency can be externally adjusted.
PIN CONNECTION (top view)
Minidip
ORDERING NUMBER : LS1241
The supply voltage is obtained from the AC ring sig-
nal and the circuit is designed to that noise on the
line or variations of the ringing signal cannot affect
correct operation of the device.
GROUND
SWEEP RATE
CONTROL CAPA CIJOR
OUTPUT FREQUENCV
CONTROL RESISTOR
RECTIFIER
CAPACITOR
BUZZER
S-6202/o
LS1 241
BLOCK DIAGRAM
TELEPHONE RECTJFIER
NBitt. 51219‘513
LINE CRPACITDR N.C. BUZZER
A n A L
a 7" z si'
' 1:2399 (1urptjT
RECTIFIER mm
BRIDGE HYSTERESIS
SUITCHING TONE
FREQUENCY FREQUENCY
GENERATOR GENERATOR
1 'T, Bi a),
uar ' V U
TELEPHONE GND SUEEP RATE OUTPUT FREQUENCY
LINE CONTROL CRPHCITOR CONTROL RESISTOR
Figure 1 :Test Circuit.
IPF 2.2Kn
LINE 7 BUZZER
10PFkTra' 1 2 3 4
cs-ll CJIL R1
s 100nT 14lrut
. 5-9047
1.90 .10 4 750
f = \__ f = - f ce40/ fSWEEP= -_.__r_-
l mm) 2 5 l D Cl mm
