MH88625 View Datasheet(PDF) - Mitel Networks

Part Name

Description

View to exact match

MH88625

DID/OPS Subscriber line interface circuit (SLIC) for on/off premise PBX line cards, DID line cards and central office cards.

Mitel Networks 

MH88625

Preliminary Information

Longitudinal Balance

The longitudinal balance specifies the degree of

common mode rejection in the 2 to 4 wire direction.

Precision laser trimming of internal resistors in the

hybrid ensures good overall longitudinal balance.

The interface circuitry can operate in the presence of

induced longitudinal currents of up to 40mA at 60Hz.

Off-Hook and Dial Pulse Detection

The SHK pin goes low when the DC-loop current

exceeds a specified level. The threshold level is

internally set by the bias voltage of the switch-hook

detect circuitry.

Dial pulse can be detected by monitoring the

interruption rate at the SHK pin. These dial pulses

would be debounced by the system’s software.

Ring Trip Detection

The interface permits detection of an Off-Hook

condition during the ringing. If the subscriber set

goes Off-Hook when the ringing signal has been

applied, the DC loop current flow will be detected

within approximately 100msecs and the SHK output

will go low. The ring relay is automatically disabled

by the internal hardware.

MH88625

Z

10kΩ

Z

-

TX 25

+

GTX1 28 RTX

GTX0 27

10kΩ

TRANSMIT GAIN:

(Tip-Ring to Tx)

AV

=

–20log





0.5

+

-5---k---Ω---

RTX





RTX

=

------------5---k---Ω---------------



10

–----A----V--

20





–

0.5

Example:

RTX = 38kΩ; AV = +4dB

Z

-

Z

+ 10kΩ

RX 26

GRX1 30 RRX

GRX0 29

10kΩ

RECEIVE GAIN:

(RX to Tip-Ring)

AV = –20log 0.5 + R-5---kR---Ω-X---

RTX = -1--0-------–----2-5-A----0---kV-----Ω----–-----0---.-5--

Example:

RRX = 4.6kΩ; AV = -4dB

2-190

Figure 3 - Gain Programming with External Components

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