PEB3265 Infineon Technologies Corporation, PEB3265 Datasheet - Page 72

• Manufacturer Part Number: PEB3265
• Description: (PEB326x / PEB426x) Dual Channel Slicofi-2 / Slic Duslic
• Manufacturer: Infineon Technologies Corporation

Preliminary
3.9
Message Waiting Indication (MWI) is usually performed using a glow lamp at the
subscriber phone. Current does not flow through a glow lamp until the voltage reaches
a threshold value above approximately 80 V. At this threshold, the neon gas in the lamp
will start to glow. When the voltage is reduced, the current falls under a certain threshold
and the lamp glow is extinguished. DuSLIC has high-voltage SLIC technology (170 V)
which is able to activate the glow lamp without any external components.
The hardware circuitry is shown in
telephone circuit with the hook switch in the on-hook mode, together with the
impedances for the on-hook (Z
Figure 36
The glow lamp circuit also requires a resistor (R
phone. When activated, the lamp must be able to either blink or remain on constantly.
In non-DuSLIC solutions the telephone ringer may respond briefly if the signal slope is
too steep, which is not desirable. DuSLIC’s integrated ramp generator can be
programmed to increase the voltage slowly, to ensure activating the lamp and not the
ringer.
Data Sheet
Message Waiting Indication (only DuSLIC-E/-E2/-P)
MWI Circuitry with Glow Lamp
Z
L
R
) and off-hook (Z
Z
R
Figure 36
R
MW
Lamp
MW
72
MW
Z
Z
R
L
L
R
MW
) modes.
) and a lamp (MW Lamp) built into the
below. The figure shows a typical
AC Impedance
Ringer Impedance
Pre Resistor Message Waiting
Functional Description
ezm14066.wmf
2000-07-14
DuSLIC