AG1110 View Datasheet(PDF) - Unspecified

Part Name

Description

Manufacturer

AG1110

LOW COST SLIC

Unspecified 

V2.5 April 2004

Data Sheet

(Motorola or Protek 1.5KE56A for -48V battery).

Alternatively, the steering diodes may be connected to

the Tranzorb clamp on its own. This avoids injecting

transients into VBAT.

6.0 A Typical Application.

The Ag1110 can interface to most Codecs, and is

shown in a typical application in Fig 5. The Codec

which has been chosen to illustrate the use of the

Ag1110 is the Texas Instruments TCM38C17 quad

device.

The TI device has no facilities for impedance matching

and is designed for low cost applications. The

impedance matching functions are therefore provided

by the SLIC circuitry. Therefore to maintain a low

solution cost and high integration, no impedance

programming components are needed, and only 600R

applications can be accommodated (unless using the

Ag1110-900, where 900R impedances can be

achieved). Where other impedances are required, an

“intelligent” codec is required such as the Legerity

QSLAC, or the Siemens SICOFI.

Figure 5 shows the usual configuration when DTMF

(tone) dialling only is used. In this case C6 is

permanently connected. If using LD dialling (also

known as loop disconnect or pulse dialling), C6 must

be switched out during dialling. Fig 6 shows a typical

circuit which could be used in such circumstances.

RDI

R7 Q1

+ C6

RT

GND

R6

C5

R8

0V

R6 = 470k

C6 = 1uF electrolytic

R7, R8 = 10k

C5 = 10nF ceramic

Q1 = general purpose transistor (eg. BC846)

Figure 6: LD Dialling Application

Ag1110

LOW COST PBX SLIC

The audio interface is extremely simple, requiring only

the d.c. blocking capacitors C3 and C4. Gains are

fixed, and therefore again no external components are

needed. NOTE: decoupling and noise suppression

components used by the TCM38C17 are not shown.

The appropriate TI data sheet should be consulted for

the correct configuration.

The switch hook detection output (SHK) from the

SLICs are passed to the microprocessor interface so

that they can then be processed as necessary by the

system software. Similarly the Ringing Relay Control

(RDI), and loop off (LO) controls are provided by the

controlling processor.

The ringing signal is provided by a central ringing

generator, through a current limiting resistor (only one

needed per line card). The PTC thermistor protects the

ringing generator against permanent short circuit. It

may not be necessary to fit a PTC where adequate

short circuit protection is already provided (eg. with

Power Dsine ringing generators).

See paragraph 1.3 for further details on ringing - a

ringing application diagram is shown in Fig 5.

6.1 Board Layout Considerations.

When laying out a circuit board, which uses the

Ag1110 it is recommended to keep all tracks as short

as possible, especially those carrying audio frequency

signals. Decoupling capacitors should be used on the

power supplies to remove unwanted noise.

The devices should be oriented to maximise the air

flow over the SLICs to remove heat. The board should

ideally arrange the SLICs in line with the natural air

flow creating a “chimney effect”.

© Silver Telecom 2004

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