
V1.0 Dec 2006
Data Sheet
Ag1171
+3.3V / +5.0V Low Power Ringing SLIC
6. Protection of the Ag1171 SLIC
6.1. Thermal Protection
Should the SLIC be operated incorrectly, for example by accidentally shorting Tip and Ring
to each other or to ground, the power dissipation is automatically limited by the DC/DC
converter
This feature means that the SLIC will always operate within its power limits, without
overheating. When operating on very short lines the battery voltage is regulated to a low
value. This limits the power dissipation and ensures the Ag1171 operates with a minimum
temperature rise.
6.2. Lightning and Power Cross Protection
The Ag1171 is designed for use short loop “on-premise” applications, such as FCT, FWT,
WLL and VoIP. In this case power cross and lightning protection is not required. The only
protection which should be required is for ESD (Electro Static Discharge) caused by
handling during installation.
The Ag1171 has been designed to be able to use low cost ESD protection components. A
typical circuit is shown in Figure 4. This circuit is suitable for most “on-premise”
applications.
7. Typical Application
The Ag1171 has been designed to interface to telephony Codecs or DSPs. Applications
drawings for many codecs and DSP chips are available. Please contact Silver Telecom or
visit our website www.silvertel.com. An example is shown in figure 4.
The status outputs from the SLIC are passed to the micro-controller. These signals can
then be processed as necessary by the system software.
The audio signals which are on the 4 wire side of the connection are coupled by capacitors
to avoid d.c. level problems between the two devices.
8. DC Supply Voltage
During operation the DC Supply Voltage MUST be regulated within the limits shown in the
Electrical Characteristics – Section 10.0 of this datasheet. Use of a “clean” power supply is
extremely important. Should the VCC supply rail go above the Absolute Maximum Rating
of 7.0V, for even a short time, then permanent damage to the Ag1171 is likely to result.
We also advise that the designer performs a full system evaluation, under all possible
performance conditions, to ensure that the VCC Maximum rating is not exceeded.
Silver Telecom 2006
10