KA2410 datasheet(3/7 Pages) ARTSCHIP

3 / 7 page

KA2410

Telephone

www.artschip.com

KA2411 Supply Current (No Load) Vs. Supply Voltage

Fig. 3

APPLICATION INFORMATION

The application circuit illustrates the use of the KA2410/1 devices in typical telephone or extensive tone ringer applications. 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 voltages (48V) on the exchange 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.

When this voltage exceeds the initiation (VSI), oscillation starts.

With the components shown, the output frequency chops between 512HZ(fH1) and 640Hz (fH2) at a 10HZ (fL) rate.

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 piezo-ceramic transducer type load, the coupling C5 and tranformer (1300Ω:8Ω) are not required.

However, a current limiting resistor if 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 tH1= 1/(1.504R3•C3) Voltage remains constant independent of

RSL.

Pin 2 of the KA2411 allows connection of an 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 supply current up to the initial voltage (VSI). This initial

voltage remains constant independent of RSL.

The supply current drawn prior to triggering varies inversely with RSL, decreasing for an 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 dropt per unit length of loop wire due to the lower current level. RSL can also be used to

compensate for smaller AC coupling capacitors (C5 on Fig. 5) (higher impedance) to the line which is used to alter the ringer

equivalence number of a tone ringer circuit.

The graph in Fig. 3 illustrates the variation of supply current with supply voltage of the KA2411. Three curves are drawn to show the

variation of initiation current with RSL. Curve B (RSL =6.8kΩ) shows the 1-V characteristic for the KA2411 tone ringer. Curve A is a plot

with RSL<6.8kΩ and shows an in the current drawn up to the initiation voltage VSI. After initiation, the I-V characteristic remain

unchanged. Curve C illustrates the effect of increasing RSL above 6.8kΩ initiation current decreases but is unchanged again after

triggering.

KA2410 Datasheet(PDF) 3 Page - ARTSCHIP ELECTRONICS CO.,LMITED.