Datasheet MT8972BC, MT8972BE, MT8971BP, MT8971BE, MT8972BP Datasheet (MITEL)

2

ISO



-CMOS ST-BUS FAMILY

MT8971B/72B

Digital Subscriber Interface Circuit

Digital Network Interface Circuit

Features

• Full duple x transm iss ion o ver a si ngle twisted pair

• Selectable 80 or 160 kbit/s line rate

• Adaptive echo c anc ellation

• Up to 3km (897 1B) a nd 4 k m (897 2B)

• ISDN compatible (2B+D) data format

• Transparent modem capability

• Frame synchronization and clock extraction

• MITEL ST-BUS compatible

• Low power (typically 50 mW), single 5V supply

Applications

• Digital subscriber lines

• High speed data transm iss ion ov er twi sted wires

• Digital PABX line cards and tel eph one set s

• 80 or 160 kbi t/s si ngle chip m odem

ISSUE 7 May 1995

Ordering In formati on

MT8971BE 22 Pin Plastic DIP MT8972BE 22 Pin Plastic DIP MT8972BC 22 Pin Ceramic DIP MT8971BP 28 Pin PLCC MT8972BP 28 Pin PLCC

-40°C to

+85°C

Description

The MT8971B (DSIC) and MT8972B (DNIC) are multi-function devices capable of providing high speed, full duplex digital transmission up to 160 kbit/s over a twisted wire pair. They use adaptive echo-cancelling techniques and transfer data in (2B+D) format compatible to the ISDN basic rate. Several modes of operation allow an easy interface to digital telecommunication networks including use as a high speed limited distance modem with data rates up to 160 kbit/s. Both devices function identically but with the DSIC having a shorter maximum loop reach specification. The generic "DNIC" will be used to reference both devices unless othe r wis e n ote d .

DSTi/Di

CDSTi/

CDi

/CLD

F0 C4/TCK

F0o/RCK

MS0 MS1

MS2

RegC

DSTo/Do

CDSTo/

CDo

Transmit Interface

Control Register

Transmit/ Clock Receive Timing & Control

Status

Receive

Interfac e

Prescrambler Scrambler

Transmit

Timi ng

Master Clock

Phase Locked

Sync Detec t

Receive

The MT8971B/72B is fabricated in Mitel’s ISO CMOS p r o cess.

Differentially

Encoded Biphase

Transmitter

Address

Echo Canceller

Error

DPLL

De-

Prescrambler

Signal

Descrambler

V

DDVSSVBiasVRef

Echo Estimate

—

+

∑

Figure 1 - Functional Block Diagram

Receive

Filter

Differenti all y

Encoded Biphase

Receiver

Transmit

Filter &

Line Driver

V

Bias

-1

+2

MUX

L

OUT

L

OUT

DIS

Precan

L

IN

OSC2

OSC1

2

-

9-1079-107

MT8971B/72B

LOUT

VBias

VRef

MS2 MS1 MS0

RegC

/CLD

F0

CDSTi/CDi

CDSTo/CDo

VSS

Pin Description

1 2

3 4 5

6 7 8

9 10 11

22 PIN PDIP/CERDIP

22 21 20 19 18 17 16 15 14 13 12

VDD LIN TEST LOUT DIS Precan OSC1 OSC2

/TCK

C4 F0o/RCK DSTi/Di DSTo/Do

RegC

F0

Figure 2 - Pin Connections

MS2

NC MS1 MS0

/CLD

NC

VRef 432

5 6 7 8 9 10 11

1213141516

CDSTi/CDi

28 PIN PLCC

VBias

CDSTo/CDo

LOUT

•

VSS

NC 1

DSTo/Do

VDD 28

17

DSTi/Di

LIN 27

/RCK F0o

TEST

26

25 24 23 22 21 20 19

18

NC

NC LOUT DIS Precan OSC1 OSC2

NC

/TCK

C4

Pin #

DIP P L CC

12 L 23 V 34 V

Name Description

OUT

Bias

Ref

Line Out. Transmit Signal output (A nalog ). Refere nced to V Internal Bias Voltage output. Connect via 0.33 µF decoupling capacit or to VDD. Internal Reference Voltage output. Connect via 0.33 µF decoupling capacitor to VDD.

Bias

.

4,5,65,7,8MS2-MS0 Mode Selec t inputs (Digital). The logi c levels present on these pins select the various

operating modes for a particular applicat ion. See Table 1 for the operating modes.

7 9 RegC Regulator Control output (Digital). A 512 kHz clock used for switch mode power

supplies. Unused in MAS/MOD mode and should be left open circuit.

810F0

/CLD Frame Pulse/C-Channel Load (Digita l). In DN mode a 244 ns wide negative pulse input

for the MASTER indicating th e start of the active channel times of the device. Output for the SLAVE indicating the start of the active channel times of the device. Output in MOD mode providing a pulse indicating the start of the C-channel.

9 12 CDSTi/

CDi

Control/Data ST-BUS In/Contr ol/Data I n (Digital). A 2.048 Mbit/ s serial cont rol & signalling input in DN mode. In MOD mode this is a continuo us bit stream at the bit rate selected.

10 13 CDSTo/

CDo

Control/Data ST-BUS Out/Control/Data Ou t (Digital). A 2.048 Mb it/s serial control & signalling output in DN mode. In MOD mode this is a continu ous bit stream at the bit rate selected.

11 14 V

SS

Negative Power Suppl y (0V ).

12 15 DSTo/Do Data ST-BUS Out/Data Out (Digital). A 2.048 Mbit/s serial PCM/data output in DN mode.

In MOD mode this is a continuous bit stream at the bit rate selected.

13 16 DSTi/Di Data ST-BUS In/Data In (Di git al). A 2.048 Mbit /s serial P CM/ dat a input in DN mode. In

MOD mode this is a continuous bit stream at the bit rate selecte d.

14 17 F0o

/RCK Fram e Pulse Ou t/Rec eive Bit Rate Clock out put (Digit al). In DN mode a 244 ns wid e

negative pulse indicating the end of the active channel times of the device to allow daisy chaining. In MOD mode provides the receive bit rate clock to the sy stem.

15 19 C4

/TCK Data Clock/Transmit Baud Rate Clock (Digital). A 4.096 MHz TTL com pat ible clock

input for the MASTER and output for the SLAVE in DN mode. For MOD mode this pin provides the transmit bit rate clo ck to the system .

16 21 OSC2 Oscillator Output. CMOS Out put.

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Pin Description (continued)

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MT8971B/72B

Pin #

DIP P L CC

Name Description

17 22 OSC1 Oscillator Input. CMOS Input. D.C. couple si gnals to this pin. Refer to D.C. Electrical

Characteristics for OSC1 input requirem ent s.

18 23 Precan Precanceller Disable. When held to Logic ’1’

precanceller is forced to V L

to the precanceller path is enabled and functions normally. An internal pulldown (50

OUT

thus bypassing the precanceller section. When logic ’0’, the

Bias

, the internal path from L

OUT

to the

kΩ) is provided on this pin.

1,6,

NC No Connection. Leave open circuit. 11, 18, 20,

25

19 24 L

OUT

DIS L

20 26 TEST Test Pin. Connect to V 21 27 L 22 28 V

F0

IN

DD

Disable. When held to logic “1”, L

OUT

“0”, L

functions normally. An internal pulldown (50 kΩ) is provided on this pin.

OUT

for normal operation.

SS

Receive Signal input (A nalog ). Positi ve P ower Supply (+5V) input .

is disabled (i.e., output = V

OUT

). When logic

Bias

C4

DSTi

DSTo

F0o

C4

DSTi

DSTo

F0

AAA

B1

7

B1

7

B1

6

B1

6

B1

5

B1

5

Channel Time 0

Figure 3 - DV Port - 80 kbit/s (Modes 2, 3, 6)

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B17B16B15B14B13B12B11B1

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B1

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7B16B15B14B13B12B11B10

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4

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3

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3

0

B1

2

B1

2

B1

1

B1

0

B27B26B25B24B23B22B21B2

B1

7

B1

7

B1

7

0

F0o

Channel Time 0

Figure 4 - DV Port - 160 kbit/s (Modes 2, 3, 6)

Channel Time 16

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MT8971B/72B

Functional Description

The MT8971B/72B is a device which has been designed primarily as an interface for the Integrated Services Digital Network (ISDN). However, it may be used in practically any application that requires high speed data transmission over two wires, including smart telephone sets, workstations, data terminals and com p uters.

L

). The data on the line is made up of information

OUT

from the DV and CD ports. The DNIC must combine information received from both the DV and CD ports and put it onto the line. At the same time, the data received from the line must be split into the various channels and directed to the proper ports. The usable data rates are 72 and for the basic rate interface in ISDN. Full duplex transmission is made possible through on board adaptive echo cancellation.

144 kbit/s as required

In the ISDN, the DNIC is ideal for providing the interface at the U reference point. The device supports the 2B+D channel format (two 64 kbit/s Bchannels and one 16 kbit/s D-channel) over two wires as recommended by the CCITT. The line data is converted to and from the ST-BUS format on the system side of the network to allow for easy interfacing with other components such as the Sinterface device in an NT1 arrangement, or to digital PABX components.

Smart telephone sets with data and voice capability can be easily implemented using the MT8971B/72B as a line interface. The device’s high bandwidth and long loop length capability allows its use in a wide variety of sets. This can be extended to provide full data and voice capability to the private subscriber by the installation of equipment in both the home and central office or remote concentration equipment. Within the subscriber equipment the MT8971B/72B would terminate the line and encode/ decode the data and voice for transmission while additional electronics could provide interfaces for a standard telephone set and any number of data ports supporting standard data rates for such things as computer communications and telemetry for remote meter reading. Digital workstations with a high degree of networking capability can be designed using the DNIC for the line interface, offering up to 160 kbit/s data transmission over existing telephone lines. The MT8971B/72B could also be valuable within existing computer networks for connecting a large number of terminals to a computer or for intercomputer links. The highest data rates existing for terminal to computer links is 19.2 kbit/s over conventional analog modems. With the DNIC, this can be increased up to 160 kbit/s at a very low cost per line for terminal to computer links and in many cases this bandwidth would be sufficient for computer to computer links.

Figu re 1 s hows the b lock diagr am of the MT897 1B/ 72B. The DNIC provides a bidirectional interface between the DV (data/voice) port and a full duplex line operating at 80 or 160 kbit/s over a single pair of twisted wires. The DNIC has three serial ports. The DV port (DSTi/Di, DSTo/Do), the CD (control/data) port (CDSTi/CDi, CDSTo/CDo) and a line port (L

IN

The DNIC has various modes of operation which are selected through the mode select pins MS0-2. The two major modes of operation are the MODEM (MOD) and DIGITAL NETWORK (DN) modes. MOD mode is a transparent 80 or 160 kbit/s modem. In DN mode the line carries the B and D channels formatted for the ISDN at either 80 or 160 kbit/s. In the DN mode the DV and CD ports are standard STBUS and in MOD mode they are transparent serial data streams at 80 or 160 kbit/s. Other modes include: MASTER (MAS) or SLAVE (SLV) mode, where the timebase and frame synchronization are provided externally or are extracted from the line and DUAL or SINGLE (SINGL) port modes, where both the DV and CD ports are active or where the CD port is inactive and all information is passed through the DV port. For a detailed description of the modes “Operating Modes” section.

In DIGITAL NETWORK (DN) mode there are three channels transferred by the DV and CD ports. They are the B, C and D channels. The B1 and B2 channels each have a bandwidth of 64 kbit/s and are used for carrying PCM encoded voice or data. These channels are always transmitted and received through the DV port (Figures 3, 4, 5, 6). The Cchannel, having a bandwidth of 64 kbit/s, provides a means for the system to control the DNIC and for the DNIC to pass status information back to the system. The C-channel has a Housekeeping (HK) bit which is the only bit of the C-channel transmitted and received on the line. The 2B+D channel bits and the HK bit are double-buffered. The D-channel can be transmitted or received on the line with either an 8, 16 or 64 kbit/s bandwidth depending on the DNIC’s mode of operation. Both the HK bit and the Dchannel can be used for end-to-end signalling or low speed data transfer. In DUAL port mode the C and D channels are accessed via the CD port (Figure 7) while in SINGL port mode they are transferred through the DV port (Figures 5, 6) along with the B1 and B2 channels.

,

see

9-110

MT8971B/72B

A

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0

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7

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6

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5

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4

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3

C

2

C

1

C

0

C

7

D

6

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5

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4

D

3

D

2

D

1

D

0

D

A

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DSTi

DSTo

15.6 µsec

F0o

B2-Channel

Channe l Tim e 3

B1-Cha nnel

Channel Time 2

C-Channel

Figure 6 - DV Port - 160 kbit/s (Modes 0,4)

Channel Time 1

D-Channel

Channel Time 0

9-111

0

D

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F0

C4

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0

B

1

B

2

B

3

B

4

B

5

B

6

B

7

B

7

C

6

C

5

C

4

C

3

C

2

C

1

C

0

C

7

D

6

D

5

D

4

D

3

D

2

D

1

D

0

D

A

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A

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A

DSTi

DSTo

11.7 µsec

F0o

B1-Cha nnel

Channel Time 2

C-Channel

Figure 5 - DV Port - 80 kbit/s (Modes 0,4)

Channel Time 1

D-Channel

Channel Time 0

F0

C4

MT8971B/72B

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In DIGITAL NETWORK (DN) mode, upon entering the DNIC from the DV and CD ports, the B-channel data, D-channel D0 (and D1 for 160 kbit/s), the HK bit of the C-channel (160kbit/s only) and a SYNC bit are combined in a serial format to be sent out on the line by the Transmit Interface (Figures 11, 12). The SYNC bit produces an alternating 1-0 pattern each frame in order for the remote en d to extract the frame alignment from the line. It is possible for the remote end to lock on to a data bit pattern which simulates this alternating 1-0 pattern that is not the true SYNC. To decrease the probability of this happening the DNIC may be programmed to put the data through a prescrambler that scrambles the data according to a predetermined polynomial with respect to the SYNC bit. This greatly decreases the probability that the SYNC pattern can be reproduced by any data on the line. In order for the echo canceller to function correctly, a dedicated scrambler is used with a scrambling algorithm which is different for the SLV and MAS modes. These algorithms are calculated in such a way as to provide orthogonality between the

F0

near and far end data streams such that the correlation between the two signals is very low.

For any two DNICs on a link, one must be in SLV mode with the other in MAS mode. The scrambled data is differentially encoded which serves to make the data on the line polarity-independent. It is then biphase encoded as shown in Figure 10. See “Line Interface” section for more details on the encoding. Before leaving the DNIC the differentially encoded biphase data is passed through a pulse-shaping bandpass transmit filter that filters out the high and low frequency components and conditions the signal for transmission on the line.

The composite transmit and receive signal is received at L

. On entering the DNIC this signal

IN

passes through a Precanceller which is a summing amplifier and lowpass filter that partially cancels the near-end signal and provides first order antialiasing for the received signal. Internal, partial cancellation of the near end signal may be disabled by holding

C4

CDSTo

CDSTi

F0o

CLD

TCK

AAA

C0C1C2C3C4C5C6C

AAA

C0C1C2C3C4C5C6C

AAA

3.9 µsec

Channel Time 0 Channel Time 16

62.5 µsec

7

D0D1D2D3D4D5D6D

125 µsec

Figure 7 - CD P ort (Mod es 2,6)

7

C

0

C

0

CDi

CDo

9-112

C

6

C

6

C

7

C

7

C

0

C

0

C

1

C

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C

2

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2

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3

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3

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4

C

4

C

5

C

5

C

6

C

6

C

7

C

7

C

0

C

0

C

1

C

1

Figure 8 - CD P ort (Mod es 1,5)

MT8971B/72B

the Precan pin high. T his mode simplifies the design of external line transceivers used for loop extension applications. The Precan pin features an internal pull-down which allows this pin to be left unconnected in applications where this function is not required. The resultant signal passes through a receive filter to bandlimit and equalize it. At this point, the echo estimate from the echo canceller is subtracted from the precancelled received signal. This difference signal is then input to the echo canceller as an error signal and also squared up by a comparator and passed to the biphase receiver. Within the echo canceller, the sign of this error signal is determined. Depending on the sign, the echo estimate is either incremented or decremented and this new es tim a te is stored ba c k i n R AM.

The timebase in both SLV and MAS modes (generated internally in SLV mode and externally in MAS mode) is phase-locked to the received data stream. This phase-locked clock operates the Biphase Decoder, Descrambler and Deprescrambler in MAS mode and the entire chip in SLV mode. The Biphase Decoder decodes the received encoded bit stream resulting in the original NRZ data which is passed onto the Descrambler and Deprescrambler where the data is restored to its original content by performing the reverse polynomials. The SYNC bits are extracted and the Receive Interface separates the channels and outputs them to the proper ports in the proper channel times. The destination of the various channels is the same as that received on the input DV and CD ports.

The Transmit/Receive Timing and Control block generates all the clocks for the transmit and receive functions and controls the entire chip according to the control register. In order that more than one DNIC may be connected to the same DV and CD ports an F0o the next device in a daisy chain that its channel times are now active. In this arrangement only the first DNIC in the chain receives the system F0 with the following devices receiving its predecessor’s F0o

.

signal is generated which signals

In MOD mode, all the ports have a different format. The line port again operates at 80 or 160 kbit/s, however, there is no synchronization overhead, only transparent data. The DV and CD ports carry serial data at 80 or 160 kbit/s with the DV port transferring all the data for the line and the CD port carryi ng the C-channel only. In this mode the transfer of data at both ports is synchronized to the TCK clocks for transmit and receive data, respectively.

The CLD C-channel data on the CD port. It is used to load and latch the input and output C-channel but has no relationship to the data on the DV port.

Operating M od es (MS0 -2)

The logic levels MS0, MS1 and MS2 program the DNIC for different operating modes and configure the DV and CD ports accordingly. Table 1 shows the modes corresponding to the state of MS0-2. These pins select the DNIC to operate as a MASTER or SLAVE, in DUAL or SINGLE port operation, in MODEM or DIGITAL NETWORK mode and the order of the C and D channels on the CD port. Table 2 provides a description of each mode and Table 3 gives a pin configuration according to the mode selected for all pins that have variable functions. These functions vary depending on whether it is in MAS or SLV, and whether DN or MOD mode is used.

The overall mode of operation of the DNIC can be programmed to be either a baseband modem (MOD mode) or a digital network transceiver (DN mode). As a baseband modem, transmit/receive data is passed transparently through the device at 80 or 160 kbit/s by the DV port. The CD port transfers the C-channel and D-Channel also at 80 or 160 kbit/s.

In DN mode, both the DV and CD ports operate as ST-BUS streams at 2.048 Mbit/s. The DV port transfers data over pins DSTi and DSTo while on the

signal goes low to indicate the start of the

present on the mode select pins

and RCK

Mode Select P in s

MS2 MS1 MS0 SLV MAS DUAL SINGL MOD DN D-C C-D ODE

00 0 0 E E E E E 00 1 1 E E E XX E 01 0 2 E E E E E 01 1 3 E E E E E 10 0 4 E E E E E 10 1 5 E E E XX E 11 0 6 E E E E E 11 1 7 E E E E

E=Enabled X=Not Applicable Blanks are disabled

Mode

Ta ble 1. Mode Select Pins

Operatin g Mode

9-113

MT8971B/72B

CD port, the CDSTi and CDSTo pins are used. The SINGL port option only exists in DN mode.

In MOD mode, DUAL port operation must be used and the D, B1 and B2 channel designations no longer exist. The selection of SLV or MAS will determine which of the DNICs is using the externally supplied clock and which is phase locking to the data on the line. Due to jitter and end to end delay, one end must be the master to generate all the timing for the link and the other must extract the timing from the receive data and synchronize itself to this timing in order to recover the synchronous data. DUAL port mode allows the user to use two separate serial

Mode Function

- The chip timebase is extracted from the received line data and the ext ernal 10. 24 MHz

- The timebase is derived from the externall y supplied data clocks and 10.24 MHz clock

- Both the CD and DV ports are active with the CD port transferring the C&D channels

- Baseband operation at 80 or 160 kbits/s. The line data is received and transmitted

- Intended for use in the digital network with the DV and CD ports operating at

SLV

MAS

DUAL

SIN GL

MOD

DN

SLAVE

crystal is phase locked to it to provide clocks for the entire device and are output for the external system to synchronize to.

MASTER

which must be frequency locked. The transmit data is synchronized to the system timing with the receive data recovered by a clock extracted from the receive data and resynchronized to the system timing.

DUAL PORT

and the DV port transferring the B1& B2 channels. SINGLE PORT - The B1& B2, C and D channels are all transferred through the DV port. The CD

port is disabled and CDSTi should be pulled high.

MODEM

through the DV port at the baud rate selected. The C-channel is transferred through the CD port also at the baud rate and is synchronized to t he CLD

DIGITAL NETWORK

2.048 Mbits/s and the line at 80 or 160 kbits/s confi gured according to the applicable ISDN recommendation.

busses: the DV port for PCM/data (B channels) and the CD port for control and signalling information (C and D channels). In the SINGL port mode, all four channels are concatenated into one serial stream and input to the DNIC via the DV port. The order of the C and D channels may be changed only in DN/ DUAL mode. The DNIC may be configured to transfer the D-channel in channel 0 and the Cchannel in channel 16 or vice versa. One other feature exists; ODE, where both the DV and CD ports are tristated in order that no devices are damaged due to excessive loading while all DNICs are in a random state on power up in a daisy chain arrangement.

output.

D-C D BEFORE C-CHANNEL C-D C BEFORE D-CHANNEL

OUTPUT DATA ENABLE

ODE

Mode

#

0F0 1CLD

2F0 3F0 4F0 5CLD 6F0 7F0

9-114

impedance state. This is intended for power-up reset to avoid bus contention and possible damage to the device during the initial random state in a daisy chain configu ratio n of DNICs. In all the other modes of operation DV and CD ports are enabled during the appropriate channel times.

F0

Name Input/Outp ut Name Inp ut/ Outp ut Nam e Input/Output

- The D-channel is transferred before the C-channel following F0.

- The C-channel is transferred before the D-channel following F0.

- When mode 7 is selected, the DV and CD ports are put in high

Table 2. Mode Definitions

/CLD F0o/RCK C4/TCK

Input F0o Output C4 Input

Output RCK Output TCK Outp ut

Input F0o Output C4 Input

Input F0o Output C4 Input Output F0o Outp ut C4 Output Output RCK Output TCK Outp ut Output F0o Outp ut C4 Output

Input F0o Output C4 Input

Ta ble 3. Pin Configurations

MT8971B/72B

DV Port (DSTi/Di, DSTo/Do)

The DV port transfers data or PCM encoded voice to and from the line according to the particular mode selected by the mode select pins. The modes affecting the configuration of the DV port are MOD or DN and DUAL or SINGL. In DN mode the DV port operates as an ST-BUS at 2.048 Mbit/s with 32, 8 bit channels per frame as shown in Figure 9. In this mode the DV port channel configuration depends upon whether DUAL or SINGL port is selected. When DUAL port mode is used, the C and D channels are passed through the CD port and the B1 and B2 channels are passed through the DV port. At 80 kbit/s only one channel of the available 32 at the DV port is utilized, this being channel 0 which carries the B1-channel. This is shown in kbit/s, two channels are used, these

Figure 3. At 160

being 0 and 16

carrying the B1 and B2 channels, respectively. This is shown in Figure 4. When SINGL port mode is used, channels B1, B2, C and D are all passed via the DV port and the CD port is disabled. See CD port description for an explanation of the C and D channels.

The D-channel is always passed during channel t ime 0 followed by the C and B1 channels in channel times 1 and 2, respectively for 80 kbit/s. See Figure

5. For 160 kbit/s the B2 channel is added and occupies channel time 3 of the DV port. See Figure

6. For all of the various configurations the bit orders are shown by the respective diagram. In MOD mode the DV and CD ports no longer operate at 2.048 Mbits/s but are continuous serial bit streams operating at the bit rate selected of 80 or 160 kbit/s. While in the MOD mode only DUAL port operation can be used.

In order for more than one DNIC to be connected to any one DV and CD port, making more efficient use of the busses, the DSTo and CDSTo outputs are put into high impedance during the inactive channel times of the DNIC. This allows additional DNICs to be cascaded onto the same DV and CD ports. When used in this way a signal called F0o

is used as an

indication to the next DNIC in a daisy chain that its channel time is now act ive . O n l y the fi r st DN IC i n th e chain receives the system frame pulse and all others receive the F0o

from its predecessor in the chain. This allows up to 16 DNICs to be cascaded.

CD Port (CDSTi/CDi, CDSTo/CDo)

The CD port is a serial bidirectional port used only in DUAL port mode. It is a means by which the DNIC receives its control information for things such as setting the bit rate, enabling internal loopback tests, sending status information back to the system and transferring low speed signalling data to and from the li ne .

The CD port is composed of the C and D-Channels. The C-channel is used for transferring control and status information between the DNIC and the system. The D-channel is used for sending and receiving signalling information and lower speed data between the line and the system. In DN/DUAL mode the DNIC receives a C-channel on CDSTi while transmitting a C-channel on CDSTo. Fifteen channel times later (halfway through the frame) a Dchannel is received on CDSTi while a D-channel is transmitted on CDSTo. This is shown in Figure 7. The order of the C and D bytes in DUAL port mode can be reversed by the mode select pins. See Table 1 for a listing of the byte orientations.

The D-channel exists only in DN mode and may be used for transferring low speed data or signalling information over the line at 8, 16 or 64 kbit/s (by using the DINB feature). The information passes transparentl y th rough the DNIC a nd i s tran smitt ed to or received from the line at the bit rate selected in the Control Register.

If the bit rate is 8 0 kbit/s , only D0 is trans mitted a nd received. At 160 kbit/s, D0 and D1 are transmitted and received . When the DIN B b it i s set i n the C on tr o l Register the entire D-channel is transmitted and received in th e B1 -channel tim e s l ot.

F0

ST-BUS

Chan nel

31

Channel0Channel1Channel

Significant

Bit (First)

Most

2

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Figure 9 - ST-BUS Format

125 µsec

• • • • • • • •

Channel

3.9 µsec

29

Channel30Channel31Channel

0

Least Significant Bit (Last)

9-115

MT8971B/72B

The C-channel is used for transferring control and status information between the DNIC and the system. The Control and Diagnostics Registers are accessed through the C-channel. They contain information to control the

DNIC and carry out the

diagnostics as well as the HK bit to be transmitted on the line as described in Tables 4 and 5. Bits 0 and 1 of the C-channel select between the Control and Diagnostics Register. If these bits are 0, 0 then the C-channel information is written to the Control Register (Table 4). If they are 0, 1 the C-

channel is

written to the Diagnostics Register (Table 5).

The Diagnostics Register Reset bit (bit 2) of the Control Register determines the reset state of the Diagnostics Register. If, on writing to the Control

bit 0 bit 1 bit 2 bit 3 bit 4 bit 5 bit 6 bit 7

Reg Sel-1 Reg Sel-2 DRR BRS DINB PSEN ATTACK TxHK

Register, this bit is set to logic “0”, the Diagnostics Register will be reset coincident with the frame pulse. When this bit is logic “1”, the Diagnostics Register will not be reset. In order to use the diagnostic features, the Diagnostics Register must be continuously written to. The output C-channel sends status information from the S tatus Register to the system along with the received HK bit as shown in Table 6.

In MOD mode, the CD port is no longer an ST-BUS but is a serial bit stream operating at the bit rate selected. It continues to transfer the C-channel but the D-channel and the HK bit no longer exist. DUAL port operation must be used in MOD mode. The Cchannel is clocked in and out of the CD port by TCK

Default Mode Selection (Refer to Table 4a)

Bit Name Description

0 Reg Sel-1 Register Select -1 . Must be set to ’0’ to select the Control Register. 1 Reg Sel-2 Register Select -2 . Must be set to ’0’ to select the Control Register. 2 DRR Diagnostics Register Reset. Writing a "0" to this bit will cause a diagnostics register reset

to occur coincident with the next frame pulse as in the MT8972A. When this bit is a logic

"1", the Diagnostics Register will not be reset. 3 BRS Bit Rate Select. When set to ’0’ selects 80 kbit/s. When set to ’1’, selects 160 kbit/s. 4DINB

➁

D-Channel in B Timeslot. When ’0’, the D-channel bits (D0 or D0 and D1) corresponding

to the selected bit rate (80 or 160 kbit/s) are transmitted during the normal D-cha nnel bit

times. When set to ’1’, the entire D-channel (D0-D7) is transmitted during the B1-channel

timeslot on the line providing a 64 kbit/s D-channel link. 5 PSEN

➁

Prescrambler/Deprescrambler Enable. When set to ’1’, the data prescrambler and

deprescrambler are enabled. When set to ’0’, the data prescrambler and deprescrambler

are disabled.

➁

6ATTACK

Convergence Speedup. When set to ’1’, the echo canceller will converge to the reflection

coefficient much faster. Used on power-up for fast convergence.

➀

When ’0’, the echo

canceller will require the normal amount of time to converge to a reflection coefficient. 7 TxHK

➁

Transmit Housekeeping. When set to ’0’, logic zero is transmitted over the line as

Housekeeping B it. When set to ’1’, logic one is transmitt ed over the line as

Housekeeping B it.

Table 4. Control Register

Notes:

➀ Suggested use of ATTACK:

-At 160 k b it/s f ul l c on v er g en ce re qu ir e s 85 0 ms with ATTACK he ld h igh fo r t he fi r st 24 0 fra me s or 30 m s.

-At 80 kb it /s fu ll conve rge nc e r eq ui res 1 .75 s with ATTA CK he ld h igh fo r t he fi r st 48 0 frames or 60 m s.

➁ Wh en bi ts 4 -7 o f the Co ntr ol Register are a ll s et to on e, the DN IC o pe rates in o ne o f th e de fau lt m od es a s de fined in Table 4a,

depend in g up on th e s t a tu s of bi t- 3.

9-116

MT8971B/72B

C-Channel

(Bit 0-7)

XXX01111 00000000 01000000 Default Mode-1

Internal Control

Regis ter

Internal Diagnosti c

Register

Description

➂

: Bit rate is 80 kbit/s. ATTACK , PSEN, DINB, DRR and all diagnostics are disabled. TxHK=0.

➃

XXX11111 00010000 01000000 Default Mode-2

Bit rate is 160 kbit/ s. ATTA CK, PSEN, DINB, DRR and all diagnostics are disabled. TxHK=0.

Table 4a. Default Mode Selection

Notes:

➂ Default M od e 1 ca n als o be selec te d by ty ing CDS Ti/C Di p in low when D N IC is ope rating i n d u al mo de . ➃ Default Mod e 2 ca n als o be selec te d by ty in g CDSTi/CD i p in h igh when DN IC is operating i n d ua l mode.

bit 0 bit 1 bit 2 bit 3 bit 4 bit 5 bit 6 bit 7

Reg Sel-1 Reg Sel-2 Loopback FUN PSWAP DLO Not Used

Default Mode Selection

(Refer to Table 4a)

Bit Name Description

0 Reg Sel-1 Register Se lect-1. Must be set to ’0’ to select the Diagnosti c Register. 1 Reg Sel-2 Register Se lect-2. Must be set to ’1’ to select the Diagnosti c Register.

2,3 Loopback Bit 2

Bit 3

0 0 A ll loopback test ing fun ctions disabled. Normal operation .

4FUN

➀

0 1 DS Ti internally looped back into DSTo for system diagnostics. 10L

is internally looped back into LIN for system diagnostics.

OUT

1 1 DS To is internally looped back into DSTi for end-to-end testing.

Force Unsync. When set to ’1’, the DNIC is forced out-of- s ync to test the SYNC

➁

➂

recovery circuitry. When set to ’0’, the operation continues in synchronization.

5 PSWAP

➀

Polynomial Swap. When set to ’1’, the scrambling and descrambling polynomials are interchanged (use for MAS mode only). When set to ’0’, the polynomials retain their normal designations.

6DLO

➀

Disable Line Out. When set to ’1’, the signal on L ’0’, L

pin functions normall y.

OUT

is set set to V

OUT

. When set to

Bias

7 Not Used Must be set to ’0’ for normal operation.

Table 5. Diagnostic Register

Notes:

➀ When bits 4-7 of the Diagnostic Register are all set to one, the DNIC operates in one of the default modes as defined in Table 4a,

depend in g up on th e s t a tu s of bi t- 3.

➁ Do not use L

to LIN loopback i n DN/ SLV mode.

OUT

➂ Do no t use DSTo to DSTi loopbac k in M OD /M AS m o de .

and CLD with TCK defining the bits and CLD the channel boundaries of the data stream as shown in Figure 8.

from the line. The line code used in the DNIC is Biphase and is shown in Figure 10. The scrambled NRZ data is differentially encoded meaning the previous differential encoded output is XOR’d with

Line Po rt (L

, L

OUT

)

IN

the current data bit which produces the current output. This is then biphase encoded where transitions occur midway through the bit cell with a

The line interface is made up of L L

driving the transmit signal onto the line and L

OUT

and LIN with

OUT

negative going transition indicating a logic "0" and a

IN

positive going transition indicating a logic "1".

receiving the composite transmit and receive signal

9-117

MT8971B/72B

01234567

SYNC CHQual Rx HK Future Functionality ID

Status

Register

Name Functio n

0 SYNC Synchronization - When set this bit indicates that synchronization to the received

line data sync patt ern has been acqui red. For DN mode only.

1-2 CHQual Channel Quality - These bits provide an estim ate of the receive r ’s margin agai nst

noise. The farther this 2 bit value is from 0 the better the SNR.

3 Rx

HK Housekee ping - This bit is the received housekeeping (HK) bit from the far end.

4-6 Future Future Fu ncti on al ity. These bits return Logic 1 when read.

7 ID This bit provides a hardware identifier for the DNIC revision. The MT8972B will return

a logic “0” for this bit. (Logic “1” returned for MT8972A.)

Table 6. Status Registe r

There are some major reasons for using a biphase line code. The power density is concentrated in a spectral region that minimizes dispersion and differential attenuation. This can shorten the line response and reduce the intersymbol interference which are critical for adaptive echo cancellation. There are regular zero crossings halfway through

The frame format of the transmit data on the line is shown in Figures 11 and 12 for the DN mode at 80 and 160 kbit/s. At 80 kbit/s a SYNC bit for frame recovery, one bit of the D-channel and the B1channel are transmitted. At 160 kbit/s a SYNC bit, the HK bit, two bits of the D-channel and both B1 and

B2 channels are transmitted. every bit cell or baud which allows simple clock extraction at the receiving end. There is no D.C. content in the code so that phantom power feed may be applied to the line and simple transformer coupling may be used with no effect on the data. It is bipolar, making data reception simple and providing a high signal to noise ratio. The signal is then passed through a bandpass filter which conditions the signal for the line by limiting the spectral content from

0.2f

Baud

to 1.6f

and on to a line driver where it is

Baud

If the DINB bit of the Control Register is set, the

entire D-channel is transmitted during the B1-

channel timeslot. In MOD mode the SYNC, HK and

D-channel bits are not transmitted or received but

rather a continuous data stream at 80 or 160 kbit/s is

present. No frame recovery information is present on

the line in MOD mode.

made available to be put onto the line biased at V

. The resulting transmit signal will have a

Bias

distributed spectrum with a peak at 3/4f transmit signal (L

DIS pin high or by writing DLO (bit 6) of the

L

OUT

) may be disabled by holding the

OUT

Baud

. The

Diagnostics Register to logic “1”. When disabled, L

is forced to the V

OUT

level. L

Bias

DIS has an

OUT

internal pull-down to allow this pin to be left not connected in applications where this function is not required. The receive signal is the above transmit signal superimposed on the signal from the remote end and any reflections or delayed symbols of the near end signal.

9-118

MT8971B/72B

Bits

Data

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

11100100

NRZ Data

Differential

Encoded

Differential

Encoded

Biphase

Transmit

Line Signal

Note: Last bit sent was a logic 0

V

Bias

F0

L

OUT

B1

7

SYNC D

Figure 11 - Frame Format - 80 kbit/s (Modes 0, 2, 3, 4, 6)

Figure 10 - Data & Line Encoding

B1

0

B1

0

B1

1

B1

2

B1

3

B1

4

B1

5

B1

6

SYNC

7

L

OUT

SYNC HK0 D1D0B10B11B12B13B14B15B16B17B20B21B22B23B24B25B26B27SYNC

Figure 12 - F rame F orma t - 160 kbit/s (Mode s 0, 2, 3, 4, 6)

9-119

MT8971B/72B

Applications

Typical connection diagrams are shown in Figures 13 and 14 for the DN mode as a MASTER and SLAVE, respectively. L coupling transformer through a resistor R2 and capacitors C2 and C2’ to match the line characteristic impedance. Suggested values of R2, C2 and C2’ for 80 and 160 kbit/s operation are provided in Figures 13 and 14. Overvoltage protection is provided by R1, D1 and D2. C1 is present to properly bias the received line signal for the L

input. A 2:1 coupling transformer is used to

IN

couple to the line with a secondary center tap for optional phantom power feed. Varistors have been shown for surge protection against such things as lightning strikes.

DV Port ST-BUS

CD Port ST-BUS

Master Clocks

Mode Select

Lines

+5V

{ { {

0.33 µF

is connected to the

OUT

MT8971B/72B

DSTi DSTo CDSTi CDSTo F0 C4 MS0 MS1 MS2 V

Ref

V

Bias

L

OUT

L

IN

OSC1

OSC2

F0o

To Next DNIC

NC

C2’ = 1.5 nF

R2 = 390Ω R1 = 47Ω

D.C. coupled, Frequen c y locke d

10.24 MHz clock. Refer to AC Electrical Characteristics

Clock Timing

DN Mode

If the scramblers power up with all zeros in them,

they are not capable of randomizing all-zeros data

sequence. This increases the correlation between

the transmit and receive data which may cause loss

of convergence in the echo canceller and high bit

error ra t e s.

In DN mode the insertion of the SYNC pattern will

provide enough pseudo-random activity to maintain

convergence. In MOD mode the SYNC pattern is not

inserted. For this reason, at least one ”1” must be fed

into the DNIC on power up to ensure that the

scramblers will randomize any subsequent all-zeros

sequence.

For 80 kbit/s: C2’ = 3.3 nF

Line Feed Voltage

1.0 µF

≈ V

IN

Bias

68 Volts (Typ)

2.5 Joules

0.02 Watt

C2 = 22 nF

+5V

D1 = D2 = MUR405

2 : 1

D2

C1 = 0.33 µF

Note: Low leakage diodes (1 & 2) are required so that the DC voltage at L

DV Port ST-BUS

CD Port ST-BUS

Master Clocks

Mode Select

Lines

+5V

9-120

0.33 µF

Figure 13 - Ty pical Connection Diagram - MAS/DN Mode , 160 kbit/s

C2’ = 1.5 nF

MT8971B/72B

{ { {

DSTi DSTo CDSTi CDSTo F0 C4 MS0 MS1 MS2 V

Ref

V

Bias

L

OUT

L

OSC1

OSC2

R2 = 390Ω R1 = 47Ω

IN

10.24 MHz XTAL

C2 = 22 nF

C3=33pF=C4

+5V

D1 = D2 = MUR405

D2

Note: Low leakage diodes (1 & 2) are required so that the DC voltage at L

2:1

1.0 µF

C1 = 0.33 µF

IN

Figure 14 - Typical Connection Diagram - SLV/DN Mode, 160 kbit/s

For 80 kbit/s: C2’ = 3.3 nF

68 Volts (Typ)

2.5 Joules

0.02 Watt

≈ V

Supply

Bias

MT8971B/72B

Absolute Maximum Ratings** - Voltages are with respect to ground (V

) unless otherwise stated.

SS

Parameter Symbol Min Max Units

1 S upply Voltage V 2 Voltage on any pin (other than sup p ly) V 3 Current on any pin (other than supply) I 4 S to rage Temperature T 5 P ackage Po wer Dissipati on

** Excee di ng these values may cause pe rm anen t damage . Function al ope rati on under the se conditi ons is not implie d.

(Derate 16mW/°C above 75°C) P

DD

Max

ST

Diss

Recommended Operating Conditions† - Voltages are with respect to ground (V

-0.3 7 V

-0.3 VDD+0.3 V

-65 +150 °C

) unless otherwise stated.

SS

Characteristics Sym Min Typ* Max Units Test Conditions

1 Operating Supply Voltage V 2 Operating Temperature T 3 Input High Voltage (except OSC1) V 4 Input Low Voltage (except OSC1) V

* Typical figures are at 25°C and are for desi gn aid only: not guarante ed and not subject to prod ucti on testin g. † Parameters over recommended temperature & power supply voltage ranges.

DC Electrical Characteristics† - Voltages are with respect to ground (V

4.75 5.00 5.25 V

DD

OP

-40 +85 °C

2.4 V

IH

IL

0 0.4 V for 400 mV noise margin

DD

SS

V for 400 mV noise margin

) unless otherwise stated.

40 mA

750 mW

Characteristics Sym Min Typ* Max Uni ts Test Conditions

1 2 Output High Voltage (ex OSC2) V 3 Output High Current 4 8 12 mA Sou rce current. V

Operating Supply Current I

(except OSC2)

DD

2.4 V IOH=10mA

OH

I

OH

10 15 mA Source current. VOH=2.4V

10 15 mA

O

5I 6 Output Low Voltage (ex OSC2) V

Output High Current - OSC 2

U

T

OH

P

7 Output Low Current

U

(except OSC2)

T

8 20 30 mA Sink current. V

S

9I

Output Low Current - OSC2 10 High Imped. Output Leakage I 11 Output Voltage (V 12 13

Input High Voltage (ex OSC1) V

(V

Ref Bias

)

I

V

OL

OZ

14 Input Low Voltage (ex OSC1) V

I

15 Input Hig h Voltage (OSC1 ) V

N

16 Input Low Voltage (OSC1) V

P

17 Input Leakage Current I

U

T

18 Input Pulld own Impedan ce

S

DIS and Preca n

L

OUT

19 Input Leakage Current for

Z

I

IOSC

10 µA Sou rce current VOH=3.5V

OL

0.4 V IOL=5mA

5 7.5 mA Sink current. VOL=0.4V

10 µA Sink current. VOL=1.5V

10 µAVIN=VSS to V

V

O

Bias

-1.8

VDD/2

2.0 V

IH IL

4.0 V

IHo ILo IL PD

50 kΩ

0.8 V

1.0 V 10 µAVIN=VSS to V

V V

20 40 µA

OSC1 Input

* Typical figures are at 25°C and are for desi gn aid only: not guarante ed and not subject to prod ucti on testin g. † Parameters over recommended temperature & power supply voltage ranges.

DD

OL

=3.0V

OH

=2.0V

9-121

MT8971B/72B

AC Electrical Characteristics† - Voltages are with respect to ground (V

) unless otherwise stated.

SS

Characteristics Sym Min Typ* Max Units Test Conditions

1

Input Voltage (L

IN)

V

IN

2 Input Current (LIN)IIN-10 +10 µAf 3 Input Impedance (L

I

N

4 Crystal/Clock Frequency f

P

5 Crystal/Clock Tolerance T

U

T

6a Crystal/Clock Duty Cycle

S

6b Crystal/Clock Duty Cycle

)ZIN20 40 kΩ f

IN

C

-100 0 +1 00 ppm

C

➀

DC DC

C

10.24 MHz

40 50 60 % Normal temp. & V 45 50 55 % Recomme nded at max./

5.0 V

pp

=160 kHz

Baud

=160 kHz

Baud

min. tem p. & V 7 Crystal/Clock Loading C 8 9 Load Resistance (L

10 Load Capacitance (L

11 Output Voltage (L

† Timing is over recommended temperature & power supply voltages. * Typical figures are at 25°C and are for desi gn aid only: not guarante ed and not subject to prod ucti on testin g. ➀ Duty cycle is measured at V

Output Capacitance (L

O U

T P U

T S

DD

(V

Bias

(V

Bias

/2 volts.

, V

OUT

Ref

OUT

Ref

OUT

)

)C

)

)V

R

C

L

o

Lout

o

0.1

3.2 4.3 4.6 V

33 50 pF From OSC1 & OSC2 to VSS.

8pF

500 100

Ω

kΩ

20 pFµFCapacitance to V

R

pp

= 500Ω, C

Lout

AC Electrical Characteristics† - Clock Timing - DN Mode (Figures 16 & 17)

DD

Bias

Lout

.

= 20pF

.

Characteristics Sym Min Typ* Max Units Test Conditions

1C4 2C4 3 Frame P ulse Se tup Time t 4 Frame Pulse Hold Time t 5 Frame Pulse Widt h t 6 10.24 MH z Clock Jitter (wrt C4

† Timing is over recommended temperature & power supply voltages. * Typical figures are at 25°C and are for desi gn aid only: not guarante ed and not subject to prod ucti on testin g. Notes: 1) When operating as a SLAVE the C4 clock has a 40% duty cycle.

F0b

C4

ST-BUS BIT CELLS

Clock Period t Clock Width High or Low t

2) When operating in MAS/DN Mode, the C4 F

=2.5xfC4). The relative p ha s e b et w ee n the se t w o c lo c ks (Φ in Fig. 17) i s no t c r it ic al an d may vary fr o m

C

0 ns to t

. How eve r, the rel ati ve j itt er m u st be less tha n JC (see Figure 17 ).

C4P

Channel 31

Bit 0

C4P

C4W

F0S

F0H

F0W

)J

C

Channel 0

Bit 7

244 ns 90 122 150 ns In Master Mode - Note 1 50 ns 50 ns

172 244 ns

-15 +15 ns Note 2

and Oscillator clocks must be externally frequency-locke d (i.e.,

Channel 0

Bit 6

9-122

Figure 15 - C4 Clock & Frame Pu lse Alig nmen t for ST-BUS Strea ms

MT8971B/72B

t

C4P

2.0V

C4

0.8V

F0

2.0V

0.8V

t

F0S

t

F0W

t

F0H

t

C4W

Figure 16 - C4 Clock & Frame Pulse Alignment for ST-BUS Streams in DN Mode

2.0V

C4

OSC1

0.8V

3.0V

2.0V

Figure 17 - Frequency Locking for the C4

Φ

J

C

and OSC1 Clocks in MAS/DN Mode

AC Electrical Characteristics† - Clock Timing - MOD Mode (Figure 18)

Characteristics Sym

80 kbit/s 160 kbit/s

Min Typ* Max Min Typ* Max

t

C4W

Units

Test

Conditions

1TCK 2 3

4CLD 5CLD 6CLD 7CLD

† Timing is over recommended temperature & power supply voltage ranges. * Typical figures are at 25°C, for de sign aid only: not guaranteed and not subject to prod ucti on testin g.

/RCK Clock Period t /RCK Clock Width

TCK

/RCK Clock Transition Time

TCK

to TCK Setup Time to TCK Hold Time Width Low Period

RCK

TCK

CLD

2.4V

0.4V

2.4V

0.4V

2.4V

0.4V

CP

t

CW

t

CT

t

CLDS

t

CLDH

t

CLDW

t

CLDP

t

CLDS

t

CLDW

12.5 6.25 µs

6.25 3.125 µs 20 20 ns CL=40pF

3.125 1.56 µs

6.05 2.925 µs

t

CLDH

8xt

CP

t

CP

8xt

CP

t

CP

t

CW

t

CW

µs

t

CT

t

CT

and CLD are generated on chip and provide the data clocks for the CD port and the transmit section of the

Note 1:

Note 2: At the slave end TCK

TCK DV port. RCK

and may be skewed with respect to TCK The rising edge of TCK

, also generated on chip, is extracted from the receive data and only clocks out the data at the Do output

due to end-to-end delay.

is phase locked to RCK.

will lead the rising edge of RCK by approximately 90o.

Figure 18 - RCK, TCK & CLD Timing For MOD Mode

9-123

MT8971B/72B

AC Electrical Characteristics† - Data Timing - DN Mode (Figu re 19)

Characteristics Sym Mi n Typ* Max Units Test Conditions

1 DSTi/CDSTi Data Setup Time t

2 DSTi/CDSTi Data Hold Time t 3a DS To/CDSTo Data Delay t 3b DS To/CDSTo High Z to Data Delay t

† Timing is over recommended temperature & power supply voltage ranges. * Typical figures are at 25°C, for design aid only: not guaranteed and not subject to producti on testin g.

Bit

Stream

2.0V

C4

0.8V

2.0V

DSTi

CDSTi

CDSTo

DSTo

0.8V

2.4V

0.4V

t

ZTD

RS

RH

TD

ZTD

TD

30 ns 50 ns

120 ns CL=40pF

100 140 ns CL=40pF

Bit Cell

t

RS

t

RH

Figur e 19 - Da ta Ti mi ng F or DN M ode

AC Electrical Characteristics† - Data Timin g - MOD Mode (Fig ure 20)

Characteristics Sym

1 Di/CDi Data Setup Time t 2 Di/CDi Data Hold Time t 3 Do Data Delay Time t 4 CDo Data Delay Time t

† Timing is over recommended temperature & power supply voltage ranges. * Typical figures are at 25°C, for design aid only: not guaranteed and not subject to producti on testin g.

DS DH RD TD

80 kbit/s 160 kbit/s

Min Typ* Max Min Typ* Max

Units

150 150 ns

4.5 2.5 µs 100 100 ns CL=40pF 100 100 ns CL=40pF

Performance Characteristics of the MT8971B DSIC

t

TD

Test

Conditions

Characteristics Sym Min Typ* Max Units Test Conditions

1 Allowable Attenuation for Bit Error

Rate of 10

-6

(Note 1)

2 Line Length at 80 kbit/s -24 AWG

-26 AWG

3 Line Length at 160 kbit/s -24 AWG

-26 AWG

A

L

80

L

160

03025dBSNR≥16.5dB (300kHz

fb

3.0

km attenuati on - 6.9 dB/k m

2.2

3.0

km attenuati on - 8.0 dB/k m

2.2

Performance Characteristics of the MT8972B DNIC

Characteristics Sym Min Typ* Max Units Test Conditions

1 Allowable Attenuation for Bit Error

Rate of 10

-6

(Note 1)

2 Line Length at 80 kbit/s -24 AWG

A

L

80

-26 AWG

3 Line Length at 160 kbit/s -24 AWG

L

160

-26 AWG

Note 1: Atte nu ation mea s ure d from M a st er L * Typical figures are at 25°C, for design aid only: not guaranteed and not subject to producti on testin g.

9-124

to Slave LIN at 3/4b au d fr eq ue n c y.

OUT

04033 dBSNR≥16.5dB (300kHz

fb

5.0

km a ttenuat ion - 6.9 dB/km

3.4

4.0

km a ttenuat ion - 8.0 dB/km

3.0

bandlimited noise)

attenuati on - 10.0 dB /km

attenuati on - 11.5 dB/km

bandlimited noise)

attenuation - 10.0 dB / km

attenuation - 11.5 dB/km

MT8971B/72B

Tx Bit

Stream

TCK

CDI

CDo

Rx Bit

Stream

RCK

Bit Cell

2.4V

0.4V t

DS

2.0V

Di

0.8V

t

TD

2.4V

0.4V

Bit Cell

t

RD

t

DH

t

TD

t

RD

Do

2.4V

0.4V

Figure 20 - Data Timing For Master Modem Mode

9-125

MT8971B/72B

2.4V

TCK

0.4V

2.0V

Di

CDI

0.8V

2.4V

CDo

0.4V

RCK

t

¼ t

CP

t

TD

DS

t

DH

t

TD

Do

2.4V

0.4V

Figure 21 - Data Timing for Slave Modem Mode

9-126

Datasheet MT8972BC, MT8972BE, MT8971BP, MT8971BE, MT8972BP Datasheet (MITEL)

Specifications and Main Features

Frequently Asked Questions

User Manual