SL2411 System Logic Semiconductor, SL2411 Datasheet - Page 6

• Manufacturer Part Number: SL2411
• Description: Tone Ringer
• Manufacturer: System Logic Semiconductor

SL2411
The application circuit illustrates the use of the SL2411 devices in typical telephone or extension tone ringer
application.
The AC ringer signal voltage appears across the TIP and RING inputs of the circuit and is attenuated by
capacitor C
C
After full wave rectification by the bridge diode, the waveform is filtered by capacitor C
for the tone ringer chip.
As this voltage exceeds the initiation voltage (V
With the components shown, the ouptut frequency chops between 512(f
The loudspeaker load is coupled through a 1300
The output coupling capacitor C
When driving a piezo-ceramic transducer type load, the coupling C
However, a current limiting resistor is required.
The low frequency oscillator oscillates at a rate (f
The frequency can be determined using the relation f
controlled by an external resistor (R
f
Pin 2 allows connection of an external resistor R
supply voltage characteristics (see Fig2), and hence the supply current up to the initiation voltage ( V
initiation voltage remains constant independent of R
The supply current drawn prior to triggering varies inversely with R
resistance. Thus, increasing the value of R
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. R
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 R
ringer.
Curve A is a plot with R
I-V characteristic after initiation remains unchanged. Curve C illustrates the effect of increasing R
initiation current decreases but again current after triggering is unchanged.
H1
1
=1/1.504R
also provides isolation from DC voltages (48V) on the exchange line.
1
3
and resistor R
xC
3
, f
H2
=1/1.203R
SL
<6.8K and shows an increase in the current drawn up to the initiation voltageV
1
.
3
xC
SL
5
3
is required with transformer coupled loads.
.
can also be used to compensated for smaller AC couplin capacitors (C
3
) and capacitor (C
SL
. Curve B( R
APPLICATION NOTE
SL
will decrease the amount of AC ringing current required to trigger the
SL
SI
L
), oscillation starts.
, which is used to program the solpe of the supply current vs
) controlled by an external resistor (R
to 8
SL
L
SL
=1/1.289R
3
.
). The frequency can be determined using the relation
=6.8K ) shows the I-V characteristic for the SL2411 tone
transformer.
2
xC
5
2
. The high frequency oscillates at a f
SL
and transformer (1300 :8 ) are not required.
, decreasing for increasing value of
h1
) and 640Hz(f
SLS
4
2
h2
) and capacitor (C
to provide a DC supply
) at a 10Hz(f
System Logic
Semiconductor
SL
above 6.8K
L
SI
) rate.
). This
H1
5
2
on Fig
, f
).
SI
. The
H2