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LS1240A LINEAR INTEGRATED CIRCUIT
ELECTRONIC TONE RINGER WITH
BUILT-IN BRIDGE RECTIFIER
DESCRIPTION
The Contek LS1240A
designed to be as a telephone ringer . It can drive directly a
piezo-ceramic converter (buzzer). The output current
capacitity of Contek LS1240A is higher than Contek LS1240, For
driving a dynamic loudspeaker , Contek LS1240A needs only a
decoupling capacitor.
isamonolithic
integrated
circuit,
FEATURES
*Low current consumption, in order to allow the parallel
operation of 4 devices.
*Integrated rectifier bridge with zener diodes to protect
against over voltage.
*Little external circuitry.
*Tone and switching frequencies adjustable by external
components.
*Integrated voltage and current hysteresis.
TEST CIRCUIT
2.2k
1 m F
W
85
7
Contek
LS1240A
10 m F
2
f1=
27200
R1(k W )
1
f2=0.725f1
3
4
C1
100nF
14k W
f ( SWEEP )=
R1
RL
750
C1(nF)
DIP-8
VoutVAB
CONTEK
Contek Microelectronics Co.,Ltd.
http://www.contek-ic.com E-mail:sales@contek-ic.com
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LS1240A LINEAR INTEGRATED CIRCUIT
ABSOLUTE MAXIMUM RATINGS(Ta=25 C)
PARAMETER SYMBOL VALUE UNIT
Calling Voltage(f=50Hz)
Continuous
Calling Voltage(f=50Hz)
5s ON/10s OFF
Supply Current IDC 30 mA
Operating Temperature Topr -20 ~ +70 C
Storage Temperature Tstg -65 ~ +150 C
Thermal Resistance
Junction-Ambient
ELECTRICAL CHARACTERISTICS
(Ta=25 C, unless otherwise specified)
PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT
Supply Voltage Vs 26 V
Current Consumption
Without load
Activation Voltage : 1240 Von 12 13.5 V
1240A Von 12 13.5 V
Sustaining Voltage :1240 VOFF 89V
1240A 7.8 9.3 V
Differential Resistance
in OFF Condition
Output Voltage Swing Vout Vs-5 V
Short Circuit Current
1240 Iout
1240A
AC Operation
Output Frequenies :
1240 fout1 V3=0V 1.65 2.53 kHz
1240A fout1 V3=0V 1.55 2.53 kHz
Fout1/Fout2 1.33 1.43 kHz
Programming Resistor Range 8 5.6
Sweep Frequency
VAB 120 Vrms
VAB 200 Vrms
Rth-amb 200 C/W
IB Vs=9.3 to 25V 1.5 1.8 mA
RD 6.4
Vs=20V,RL=0 W
RL=250W
Vs=26V,R1=14k W
fout2 Vs=6V 1.15 1.9 kHz
fout2 Vs=6V 1.08 1.9 kHz
C1=100nF,R1=14k W
89V
7.8 9.3 V
5.25 7.5 9.75 Hz
kW
kW
CONTEK
Contek Microelectronics Co.,Ltd.
http://www.contek-ic.com E-mail:sales@contek-ic.com
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LS1240A LINEAR INTEGRATED CIRCUIT
PIN CONFIGURATIONS
Contek
LINE
1
LINE
8
GROUND
2
RECTIFIER
7
CAPACITOR
SWEEP RATE
CONTROL
CAPACITOR
3
NULL
6
OUTPUT
FREQUENCY
CONTROL
4
5
BUZZER
RESISTOR
APPLICATION CIRCUIT
1 mF
2.2kW
LINE
7
Contek LS1240
10mF
123 4
58
C1
100nF
R1
14kW
BUZZER
Zload>1k
W
No current limitation is provided on the output stage of ContekLS1240A,so a minimum load DC of 50 ohms is
adviced.
The two tone frequencies generated are switched by an internal oscillator in a fast sequence and made audible
across an output amplifier in the loudspeaker, both tone frequencies and the switching frequency can be externally
adjusted.The signal and the circuit is designed so that noise on the lin or variations of the ringing signal cannot affect
correct operation of the device.
LINE
1 mF
10mF
2.2kW
7
85
ContekLS1240A
1 2 3 4
C1
100nF
R1
14kW
CL
RL=50W to
1000W
CONTEK
Contek Microelectronics Co.,Ltd.
http://www.contek-ic.com E-mail:sales@contek-ic.com
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