MH88628 Просмотр технического описания (PDF) - Mitel Networks

Номер в каталоге

Компоненты Описание

производитель

MH88628

Central Office SLIC

Mitel Networks 

MH88628

Preliminary Information

+5V

LCA

8a

R

LCA

8b

R

-5V

Loop Current Setting

Figure 8 - Loop Current Setting

LCA

8c

High Voltage capability

Loop Length

Inherent in the thick-film process is the ability of the

substrate to handle high voltage. The standard Mitel

thick-film process provides dielectric strengths of

greater than 1000VAC or 1500VDC. The thick-film

process allows easy integration of surface mount

components such as the high voltage bi-polar power

transistor line drivers. This allows for simplier, less

elaborate and less expensive protection circuitry

required to handle high voltage transients and fault

conditions caused by lightning, induced voltages and

power line crossings.

On-hook Transmission

The MH88628 provides for on-hook transmission

which supports features such as Automatic Numbers

Identification (ANI). The (ANI) information is a FSK

signal originating from and sent by the C.O. during

the off period of the ringing voltage being sent to the

subscribers set. The signal is present during the off

period between the first and second ring. The

subscribers set decodes the FSK signal and displays

the calling party’s number.

TIP Disable

A relay driver, controlled by SEL1 and SEL2, is

provided to drive a relay which can be used to

disable the TIP line when the MH88628 is used for a

ground start central office interface.

The MH88628 can accommodate loop length of up to

2300Ω minimum (including the subscriber

equipment). This corresponds to approximately 8km

using 26AWG twisted pair or 15km using 24AWG

twisted pair.

Central Office Operation

The MH88628 can be configured for ground start

C.O. applications with the addition of Q1, D1 and K2,

as shown in Figure 9. Ground start requires control of

the Tip lead to remove battery ground from

subscriber loop. For loop start applications, control of

the Tip lead is not required.

C.O’s perform Tip/Ring reversals to indicate that a

tool call has been dialled. The Tip/ring reversal can

indicate a toll diversion signal.

Internal Ringing Amplifier Operation

The MH88628 offers an on-board ringing amplifier. A

1.5 VRMS, 20Hz signal is amplified internally and

applied to TIP and RING leads in a balanced

configuration. A +120Vdc supply are applied

continuously to the MH88628. The decode signals on

SEL1 and SEL2 enable the ringing signal to the TIP

and RING when required.

2-210

Share Link: