LINEAR INTEGRATED CIRCUIT
ELECTRICAL CHARACTERISTICS( Ta=25°C )
(All voltage referenced to GND unless otherwise specified)
Operating Supply Voltage
Initiation Supply Voltage1
Initiation Supply Current1
6.8K-Pin 2 to GND
Isus No Load Vcc=Vsus,See Fig.2
Output Voltage High
VOH Vcc=21V, I8=-15mA
Output Voltage Low
VOL Vcc=21V, I8=15mA
High Frequency 1
High Frequency 2
FH1 R3=191K, C3=6800pF
FH2 R3=191K, C3=6800pF
FL R2=165K, C2=0.47µF
Min Typ. Max Unit
17 19 21
1.4 2.5 4.2 mA
9.7 11.0 12.0 V
0.7 1.4 2.5 mA
17.0 19.0 21.0 V
ü ü 500 nA
ü ü 500 nA
461 512 563 Hz
576 640 704 Hz
9.0 10 11.0 Hz
*NOTE (See electrical characteristics sheet)
1. Initiation supply voltage (Vsi) is the supply voltage required to start the tone ringer oscillating.
2. Sustaining voltage (Vsus) is the supply voltage required to maintain oscillation.
The application circuit illustrates the use of the UTC2411 device in typical telephone tone ringer
The AC ringer signal voltage appears across the TIP and RING inputs of the circuit and is attenuated by
capacitor C1 and resistor R1.
C1 also provides isolation from DC voltage (48V) on the exchanged line.
After full wave rectification by the bridge diode, the waveform is filtered by capacitor C4 to provide a DC
supply for the tone ringer chip.
As this voltage exceeds the initiation voltage (Vsi), oscillation starts.
With the components shown , the output frequency chops between 512Hz (FH1) and 640 Hz(FH2) at a 10
The loudspeaker load is coupled through a 1300Ω to 8Ω transformer.
The output coupling capacitor C5 is required with transformer coupled loads.
When driving a pizeo-ceramic transducer type load, the coupling C5 and transformer (1300Ω:8Ω) are not
However, a current limiting resistor is required.
The low frequency oscillator oscillates at a rate (FL) controlled by an external resistor (R2) and capacitor (C2).
The frequency can be determined using the relation FL=1/1.289 R2* C2. The high frequency oscillates at a
FH1,FH2 controlled by an external resistor (R3) and capacitor (C3). The frequency can be determined using the
relation FH1=1/1.504 R3*C3 and FH2= 1/1.203 R3*C3.
Pin 2 of the UTC2411 allows connection of external resistor RSL, which is used to program the slope of the
supply current vs supply voltage characteristics (see Fig.3), and hence the supply current up to the initiation
voltage (Vsi). This initiation voltage remains constant independent of RSL.
The supply current drawn prior to triggering varies inversely with RSL, decreasing for increasing value of
resistance. Thus, increasing the value of RSL, will decrease the amount of AC ringing current required to trigger
the device. As such, longer subscriber loops are possible since less voltage is dropped per unit length of loop wire
due to the lower current level. RSL can also be used to compensated for smaller AC coupling capacitors (C5 on
Fig.4) (higher impedance) to the line which can be used to alter the ringer equivalence number of a tone ringer
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