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AG1170

+5V / +3.3V Low Power Ringing SLIC

Unspecified 

V1.9 September 2006

Data Sheet

Ag1170

+5V / +3.3V LOW POWER RINGING SLIC

5.2 Lightning and Power Cross Protection.

It is usual for the Ag1170 to be used in “on-premise”

applications, such as SOHO, CTI and VoIP. In this

case power cross and lightning protection is not

required. In most ‘off-premise’ applications, a

subscriber circuit will be required to withstand over

voltage conditions which could be caused by lightning

or overhead power cables striking the telephone

cables. It is therefore normal in “off-premise”

applications to provide primary and secondary

protection circuits to prevent damage to the SLIC.

The Ag1170 has been designed to be able to use low

cost protection components, a typical circuit is shown

in Figure 5. This circuit is suitable for most “on-

premise” applications.

With some additional components, the Ag1170 will

meet UL60950 requirements: a series element should

be added - a combination of a fuse (e.g. 350mA,

Bussman C515 or Littlefuse 220003) and a surge

resistor (25R typically). Alternatively a Teccor F1250T

or F0500T fuse may be used without a surge resistor.

For ITU-T K20 power cross protection, a PTC

thermistor (eg. type JH330L) of 30R is suitable. The

lightning protection is provided by steering diodes

connected to 0V and upgrading D1 to a Tranzorb

device (Motorola or STM 1.5KE82A). For lightning and

UL60950 power cross protection, D1 should be

upgraded further (General Semiconductor or Semitron

5KP75). Just one Tranzorb is needed per linecard.

6.0 Approvals.

It can be seen from the Electrical Characteristics given

on subsequent pages that the SLIC has been designed

to meet the equipment standards of as many major

public telephone authorities as possible.

It is the responsibility of the equipment design authority

to ensure that their system meets the requirements of

the relevant regulatory bodies. Every effort is made to

ensure that Silver Telecom products are compliant with

the latest standards.

The Ag1170 provides for a 2 wire impedance and a

network balance impedance of 600Ω. For other

impedances the Ag1170-P can be used. This can be

programmed using external components (Section 3.2

and 3.3).

7.1 DC Supply Voltage

During operation the DC Supply Voltage MUST be

regulated within the limits shown in the Electrical

Characteristics – Section 9.0 of this datasheet. Use of

a “clean” power supply is extremely important. Should

the VCC supply rail go above the Absolute Maximum

Rating of 5.5V, for even a short time, then permanent

damage to the Ag1170 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.

In some applications, additional EMI suppression may

be needed. In this instance 3 capacitors can be added

to filter out the higher frequencies of the DC-DC

converter. See figure 6 for details.

1nF

1nF

AAg11117700

Tip

Ring

ZB

VOUT

100pF

Figure 6: Optional EMI Suppression

7.0 A Typical Application.

The Ag1170 has been designed to interface to any

Codec. 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 5.

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 100nF capacitors to avoid

d.c. level problems between the two devices.

© Silver Telecom 2006

9

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