UTC LS1240A LINEAR INTEGRATED CIRCUIT
UTC
UNISONIC TECHNOLOGIES CO., LTD.
1
QW-R108-002,D
ELECTRONIC TONE RINGER WITH
BUILT-IN BRIDGE RECTIFIER
DESCRIPTION
The UTC LS1240A is a monolithic integrated circuit,
designed to be as a telephone ringer. It can drive directly a
piezo-ceramic converter (buzzer). The output current capacity
of UTC LS1240A is higher than UTC LS1240, For driving a
dynamic loudspeaker, UTC LS1240A needs only a
decoupling capacitor.
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.
DIP-8
SOP-8
TEST CIRCUIT
R1=
27200
f1(Hz)
f2=0.725f1
f
SWEEP
=
750
C1(nF)
2.2k
1
F
10
F
C1
100nF
R1
14k
RL
Vout
V
AB
8
5
7
1
2
3
4
UTC LS1240A
*(1-0.04 In
f1
1943
)
UTC LS1240A LINEAR INTEGRATED CIRCUIT
UTC
UNISONIC TECHNOLOGIES CO., LTD.
2
QW-R108-002,D
ABSOLUTE MAXIMUM RATINGS
(Ta=25
C)
PARAMETER SYMBOL
VALUE UNIT
Calling Voltage(f=50Hz)
Continuous
V
AB
120
Vrms
Calling Voltage(f=50Hz)
5s ON/10s OFF
V
AB
200
Vrms
Supply Current
I
DC
30
mA
Operating Temperature
Topr
-40 ~ +70
C
Storage Temperature
Tstg
-65 ~ +150
C
Thermal Resistance
Junction-Ambient
Rth-amb 200
C/W
ELECTRICAL CHARACTERISTICS
(Ta=25
C, unless otherwise specified)
PARAMETER SYMBOL
TEST
CONDITIONS
MIN
TYP
MAX
UNIT
Supply Voltage
V
s
26 V
Current Consumption
Without load
I
B
Vs=9.3 to 25V
1.5
1.8
mA
Activation Voltage : 1240
Von
12
13.5
V
1240A
Von
12
13.5
V
Sustaining Voltage :1240
V
OFF
8 9 V
1240A
7.8
9.3
V
Differential Resistance
in OFF Condition
R
D
6.4
k
Output Voltage Swing
Vout
Vs-5
V
Short Circuit Current
1240
1240A
Iout
Vs=20V, RL=250
70
70
mA
mA
AC
Operation
Output Frequencies :
Vs=26V,R1=14k
1240
fout1
V3=0V
1.65
2.53
kHz
fout2
Vs=6V
1.15
1.9
kHz
1240A
fout1
V3=0V
1.55
2.53
kHz
fout2
Vs=6V
1.08
1.9
kHz
Fout1/Fout2
1.33
1.43
Programming Resistor Range
8
56
k
Sweep Frequency
C1=100nF,R1=14k
5.25
7.5 9.75 Hz
UTC LS1240A LINEAR INTEGRATED CIRCUIT
UTC
UNISONIC TECHNOLOGIES CO., LTD.
3
QW-R108-002,D
PIN CONFIGURATIONS
1
2
3
4
8
7
6
5
LINE
GROUND
SWEEP RATE
CONTROL
CAPACITOR
OUTPUT
FREQUENCY
CONTROL
RESISTOR
LINE
RECTIFIER
CAPACITOR
NULL
BUZZER
APPLICATION CIRCUIT
2.2k
1
F
10
F
C1
100nF
R1
14k
LINE
BUZZER
Zload>1k
5
8
7
1
2
3
4
UTC LS1240
2.2k
1
F
10
F
C1
100nF
R1
14k
LINE
8
5
7
1
2
3
4
CL
RL=50
to
1000
UTC LS1240A
No current limitation is provided on the output stage of UTC LS1240A, so a minimum load DC of 50 ohms is
advised.
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 line or variations of the ringing signal cannot
affect correct operation of the device.
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