TS31002

Tong Ringer

5/8

Version: A07

Application Note

Pin 2 allows connection of an external resistor RSL, which is used to program the slope of the supply current vs supply

voltage characteristics (see Fig2), 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 sucribser 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 compensate for smaller AC couplin capacitors (C5 on Fig 3) (higher impedance) to the

line which can be used to alter the ringer equivalence number of a tone ringer circuit.

The graph in Fig2 illustrates the variation of supply current with supply voltage. Three curves are drawn to show the

variation of initiation current with RSL. Curve B( RSL=6.8KΩ) shows the I-V characteristic for the TS31002 tone ringer.

Curve A is a plot with RSL<6.8KW and shows an increase in the current drawn up to the initiation voltage VSI. The

I-V characteristic after initiation remains unchanged. Curve C illustrates the effect of increasing RSL above 6.8KW

initiation current decreases but again current after triggering is unchanged.

Characteristics Curve

Figure 4.

Figure 5.