MITEL MH89625C, MH89625C-5, MH89625C-6 Datasheet

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MH89625C

OPS/DID PCM SLIC

Preliminary Information

Features

• Input impe dance v aria nts:

- 600Ω

- 200Ω + 680Ω // 0.1µF

- 200Ω + 560Ω // 0.1µF

• Operates wi th a wide rang e of bat tery vol tag es

• Constant current battery feed with constant voltage fall back for long l oop dri ve ca pabiliti es

• Overvoltag e and s hort circuit pro tect ion

• Off-hook detection and LED indicator drive

• Dial pulse detection

• Ring trip filter with auto ring trip

• Ring relay dr iver pl us thre e mor e uncom mitte d relay drivers

• Transformerless 2W to 4W conversion

• A/D and D/A c onvers ion

• Conforms to A-Law PCM

• Analog and digi tal loop ba ck

• Conforms to CC ITT k .20 overv olta ge su rge requirements with external primary protection circuitry

Applications

• Off premise digital PBX line cards

• DID (Direct Inward Dial) lin e cards

• PABX, Key Systems, Central Office Equipment

ISSUE 4 May 1995

Ordering Information

MH89625 C 600Ω MH89625C- 5 200Ω + 680Ω // 0.1µF MH89625C- 6 200Ω + 560Ω // 0.1µF

40 Pin DIL Package

Description

The Mitel MH89625C SLIC (Subscriber Line Interface Circuit) provides a complete interface between an off-premise telephone line and a digital switching system. All BORSCHT functions of Battery Feed, Overvoltage Protection, Ringing Feed, Line Supervision, Codec, 2-4 Wire Hybrid and Test are provided requiring only a few external components. The input impedance conforms with Chinese standard requirements. The device is fabricated using thick film hybrid technology which incorporates various technologies for high voltage capability, optimum circuit design and very high reliability.

TIP

RING

RF2

RF1

VBat LGND LCA GS

Tip

Drive

Current

& Voltage

Sensin g

Ring

Drive

Supervision

LED

Constant Current &

Voltage

Control

Ring

Trip

Filter

Line

Gain

Adjust

2w/4w

hybrid

Impedance

Matching

Relay

Driver 1

RD1SHK

Figure 1 - Functional Block Diagram

Relay

Driver 2

Relay

Driver 3

RD3RD2

VREF CA

VREF

CODEC

DSTo

DSTi

CSTi

SD2SD1SD0

Relay

Driver 4

RD4

F1i CS

SD3

DSTi DSTo

CSTi

F1i C2i

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MH89625C Preliminary Information

TIP

RING

IC IC

IC RF1 RF2

VEE SHK

LED CSTi DSTi

C2i

DSTo

F1i CA

RGND

RD2

RD1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

40 39

38 37

36 35

34 33 32 31 30 29 28 27 26 25 24 23 22 21

IC IC IC VBAT LGND GS VAC IC LCA VDD AGND IC IC IC IC IC VREF VRLY RD4 RD3

Figure 2 - Pin Connections

Pin Description

Pin # Name Description

1TIPTip Lead. Connects to the “Tip” lead of the telephone line. 2 RING Ring Lead. Connects to the “Ring” lead of the telephone lin e. 3ICInternal Connection : This pin is internally connected. 4ICInternal Connection : This pin is internally connected. 5ICInternal Connection : This pin is internally connected. 6RF1Ring Feed 1: For OPS operation, connects to the external battery backed ringing

generator, see Figure 2.

7RF2Ring Feed 2: For OPS operation, connects to RING through a normal ly closed relay

contact (K1), see Figure 2. 8ICInternal Connection. This pin is internally connected. 9V

10 SHK 11 LED

Negative Supply Voltage: (-5V)

Switch Hook Detect (Output): A logic low indicates an off-hook condition.

LED Drive (Output ): Drives an LED directly through an internal 2.2kΩ resistor. A logic

low indicates an off-hook condition.

12 CSTi Control ST-BUS in (Input): A TTL compatible digi tal input used to control the function

of the filter/codec. Three mode s of operati on may be affected by applying to this input

logic high, logic low or an 8-bit serial word, depending on the logic states of CA and F1i.

Functions controlled are: power down, filt er gain adjust , loopbac k, chip testing, and the

SD outputs which control the relay drivers, ring trip circuitry and impedance selection.

13 DSTi Data ST-BUS in (Input): A TTL compatible digital input which accepts the 8-bit PCM

word from the incoming PCM bus.

14 C2i Clock Input (Input): A TTL compatible dig ital input which accepts the 2048 kHz clock. 15 DSTo Data ST-BUS Out (Output). A three stage TTL compa tible digit al out put which drive s

the 8-bit PCM word to the outgoing PCM b us.

16 F1i Synchronization Input (Input): A TTL compatible active low digi tal input enabling (in

conjunction with CA) the PCM input, PCM out put and digit al control input. It is internally

sampled on every positive edge of the clock, C2i, and provides frame and channel

synchronizati on.

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Preliminary Information MH89625C

Pin Description (Contin ue d)

Pin # Name Description

17 CA Control Address (Input): A three-level digital input which enables PCM input and

output, and determi nes into whi ch control registe r (A or B) the serial dat a, present ed to

CSTi, is stored. 18 RGND Relay Gro und: Return path for relay supply voltage. 19 RD2

Relay Driver 2: Connects to a user provided external relay coil. A logic high at the SD1

output of the internal MT8967 codec activate s this driver. An internal clamp diode from

is provided. This relay is typically used for DID reversals.

20 RD1

VRLY to RD2

Relay Driver 1. Connects to a user provided external relay coil. A logic high at the SD0

output of the internal MT8967 codec activate s this driver. An internal clamp diode from

is provided. This relay is typically used for ringing.

21 RD3

VRLY to RD1

Relay Driver 3. Connects to a user provided external relay coil. A logic high at the SD2

output of the internal MT89 67 codec activate s this drive r. An internal clamp diode from

is provided. This relay is typically used for in-test.

22 RD4

VRLY to RD3

Relay Driver 4: Connects to a user provided external relay coil. A logic high at the SD3

output of the internal MT8967 codec activate s this driver. An internal clamp diode from

is provided. This relay is typically used for out-test.

23 V

RLY

VRLY to RD4

Relay Positive Supply Voltage: Normally +5V. Connects to the relay coil and the relay

supply voltage. 24 V

Ref

Voltage Reference (Input): +2.50V for the internal codec. 25 IC Internal Connec tion: This pin is internally connected. 26 IC Internal Connec tion: This pin is internally connected 27 IC Internal Connec tion: This pin is internally connected 28 IC Internal Connec tion: This pin is internally connected 29 IC Internal Connec tion: This pin is internally connected 30 AGND Analog Gro und . Analo g and Digital Ground. Connects to System Ground. 31 V

Positive Supply V o ltage (+5V) 32 LCA Loop Current Adjust (Input). The maximum constant loop current is a function of the

resistance connected from this pin to V

. Normally left open

33 IC Internal Connec tion. This pin is internally connected. 34 VAC Battery AC Component (Input). AC noise present in the V

supply, isolated from the

BAT

DC component, can be applied to this pin to reduce longitudinal noise on TIP and RING.

To implement this feature, connect a 0.1µF 100V capacitor from V

to VAC, and a 1kΩ

BA T

resistor from VAC to AGND. This pin must be tied to AGND when not used. 35 GS Gain Setting (In put). A logic low at this input adds an additio nal -0.5d B gain in the

receive direction (DSTi to Tip-Ring). This gain is in addition to the gain set by the Codec.

A logic high adds 0dB gain. 36 LGND Loop Ground. Return path for the batt er y (V

) supply voltage. Connects to System

BAT

Ground.

37 V

Bat

Battery Supply Voltage. Normally -48V. 38 IC Internal Connec tion: This pin is internally connected 39 IC Internal Connec tion: This pin is internally connected 40 IC Internal Connec tion: This pin is internally connected

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MH89625C Preliminary Info rm atio n

Functional Desc ription

The Mitel MH89625C OPS SLIC (Off-Premise Subscriber Line Interface Circuit) provides a complete interface between an off-premise telephone line and an digital switching system. All BORSCHT functions are provided requiring only a few external components. The input impedance conforms with Chinese standard requirements.

All functions of the SLIC are controlled by the system Drive (SD) outputs of the internal Mitel A-Law Codec MT8967. The SD outputs are controlled by the serial data input stream at CSTi.

The BORSCHT Functions

The MH89625C performs all of the BORSCHT functions of Battery Feed, Overvoltage Protection, Ringing, Supervision, Codec, Hybrid and Test.

Battery Feed

Ringing

The ringing insertion circuit has the capability to provide ringing voltage to a telephone set by simply adding an external relay, ring generator and a transient protector. The internal relay driver switches ringing voltage onto the line via the external ring relay. A clamp diode is included which suppresses voltage transients during relay switching caused by the relay coil. The serial data input at CSTi controls the internal Codec’s SDo output which activates the ring driver. Refer to Table 1 for control of SLIC functions.

Supervision

The loop detection circuit determines whether a low enough resistance is across Tip and Ring to be recognized as an off-hook condition. When an off-hook condition occurs, the SHK LED

output can drive an LED directly) outputs toggle to a low level. These outputs also toggle with incoming dial pulses.

and LED (the

The MH89625C powers the telephone set with constant DC loop current for short lines and automatically reverts to constant voltage for long lines. The constant loop current is a function of the resistance connected from the LCA pin to V

Where I

147.2 -I

R =

(0.0001176 X I

is the desired constant loop current in mA,

Loop

) -0.002586

Loop

and R is the resistance from pin LCA to pin V

EE.

ohms.

R (kΩ)

Loop

(mA)

open 348k 200k

80k 50k 30k

22.0 25.0 27.1 34.0 40.2 49.7

Overvoltage Pr otection

The MH89625C is protected from short term (20ms) transi ents (+ ground, and RING and ground. However, additional protection circuitry may be needed depending on the requirements which must be met. Normally simple external shunt protection as shown in Figure 4 is all that is required.

250V) between TIP and RING, TIP and

During applied ringing (ring relay driver activated), the loop detection circuit engages a ringing filter. This filter prevents false off-hook detection due to the current associated with the AC ringing voltage as well as current transients that occur when the ringing voltage is switched in and out. The ring trip detection circuitry deactivates the ring relay driver after an off-hook condition is detected.

Codec

The Codec function of the SLIC is implemented using the Mitel MT8967 A-Law Codec. This device provides the conversion interface between the voiceband analog signals of a telephone subscriber loop and the digital signals required in a digital PCM (pulse code modulation) system. Eight-bit PCM encoded digital data enters and leaves the chip serially on DSTi and DSTo pins, respectively.

For detailed information on the CODEC portion of the MH89625C, refer to the MT8967 integrated PCM Filer/Codec data sheet (Microelectronics Digital Communications Handbook, Mitel Semiconductor Issue 9).

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Preliminary Information MH89625C

Absolute Maximum Ratings* - All voltages are with respect to AGND unless otherwise specified.

Parameter Symbol Min Max Units

1 DC Supply Voltage V

2 DC Battery Voltage ① V 3 DC Ring Relay Voltage V 4 DC Reference Voltage V

DD EE

BAT

RLY

REF

-0.3

0.3

0.3 -65 V

-0.3 7 V

-0.3 V

-7

5 AC Ring Generator Voltage 150 V 6 DC Digital Input Voltage

GS, CSTi

-0.3 V

DSTi, C2i

F1i

7 DC Digital (3-level) Input voltage CA V

8 Storage Temperature TS -40 +125 °C

* Exceeding these values ma y cause perm anen t dama ge. Functi onal operati on und er these cond ition s is not implied. ① LGND is c o nn ec te d t o AGND

Recommended Operating Conditions

Paramete rs Sym Min Typ

‡

Max Units Test Conditions

RMS

1 DC Supply Voltages V

2 DC Battery Voltage ① V 3 DC Ring Relay Voltage V

4 DC Reference Voltage ② V 5 AC Ringing Generator

Voltage

DD EE

BAT

RLY

REF

4.75

-4.75

5.0

-5.0

5.25

-5.25

-39.8 -48 -60 V

5.0 7 V

2.488 2.500 2.512 V 22 90

130

V V

RMS

Ringing Generator Frequency

6 Operating Temperature T

① LGND is c o nn ec te d t o AGND. ② Temperature coefficient of V

‡ Typical figures are at 25°C and are for desi gn aid only: not gua rantee d and not subje ct to producti on testing.

should be better than 100ppm/C.

REF

02570°C

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