TS31002_07 Datasheet, PDF (5/8 Pages) Taiwan Semiconductor Company, Ltd – Tong Ringer

TS31002
Tong Ringer
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.
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Version: A07