LXT312A/LXT315A

Low Power T1 PCM Repeaters/Transceivers

Datasheet

This data sheet also applies to the LXT312/LXT315 products.

The LXT312A and LXT315A are integrated repeater/transceiver circuits for T1 carrier systems.
The LXT312A is a dual repeater/transceiver and the LXT315A is a single repeater/transceiver.
The LXT312A and LXT315A are designed to operate as regenerative repeaters/transceivers for
1.544 Mbps data rate PCM lines. Each includes all circuits required for a regenerative repeater/
transceiver system including the equalization network, automatic line build-out (ALBO), and a
state-of-the-art analog/digital clock extraction network tuned by an external crystal.

The key feature of the LXT312A family is that it requires only a crystal and a minimum of other
components to complete a repeater/transceiver design. Compared with traditional tuned coil-
type repeaters/transceivers, they offer significant savings in component and labor costs, along
with reduced voltage drop/power consumption, and improved reliability. To ensure performance
for all loop lengths, the LXT312A and LXT315A are 100% AC/DC tested using inputs
generated by Intel's proprietary transmission line and network simulator.

The LXT312A and LXT315A are advanced CMOS devices which require only a single 5-volt
power supply.

Product Features

Integrated repeater/transceiver circuit on a
single CMOS chip

On-chip equalization network

On-chip ALBO

Low power consumption

No tuning coil

On-chip Loopback

Recovered Clock Output

0 to 36 dB dynamic range

-11 dB interference margin

Compatible with CB113/TA24
specifications

Single 5 V CMOS technology

Available in 16-pin PDIP and 44-pin PLCC

As of January 15, 2001, this document replaces the Level One document

Order Number: 249071-001

LXT312A/LXT315A -- Low Power T1 PCM Repeaters/Transceivers.

January 2001

Datasheet

Information in this document is provided in connection with Intel

products. No license, express or implied, by estoppel or otherwise, to any intellectual

property rights is granted by this document. Except as provided in Intel's Terms and Conditions of Sale for such products, Intel assumes no liability
whatsoever, and Intel disclaims any express or implied warranty, relating to sale and/or use of Intel products including liability or warranties relating to
fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. Intel products are not
intended for use in medical, life saving, or life sustaining applications.

Intel may make changes to specifications and product descriptions at any time, without notice.

Designers must not rely on the absence or characteristics of any features or instructions marked "reserved" or "undefined." Intel reserves these for
future definition and shall have no responsibility whatsoever for conflicts or incompatibilities arising from future changes to them.

The LXT312A/LXT315A may contain design defects or errors known as errata which may cause the product to deviate from published specifications.
Current characterized errata are available on request.

Contact your local Intel sales office or your distributor to obtain the latest specifications and before placing your product order.

Copies of documents which have an ordering number and are referenced in this document, or other Intel literature may be obtained by calling 1-800-
548-4725 or by visiting Intel's website at http://www.intel.com.

*Third-party brands and names are the property of their respective owners.

Datasheet

Low Power T1 PCM Repeaters/Transceivers -- LXT312A/LXT315A

Contents

1.0

Pin Assignments and Signal Descriptions

...................................................... 6

2.0

Functional Description

............................................................................................. 8

2.1

Introduction............................................................................................................ 8

2.2

Receive Function................................................................................................... 8
2.2.1

Timing Recovery Function........................................................................ 8

2.3

Transmit Function.................................................................................................. 8

2.4

Loopback Function
(LXT312A Only)9

3.0

Application Information

.........................................................................................10

3.1

Introduction.......................................................................................................... 10
3.1.1

Alternate Timing Reference.................................................................... 10

4.0

Test Specifications

.................................................................................................. 12

4.1

Test Setups ......................................................................................................... 13
4.1.1

Introduction............................................................................................. 13

4.1.2

Receiver Jitter Tolerance Testing........................................................... 13

4.1.3

Receiver Jitter Transfer Testing ............................................................. 13

4.1.4

Interference Margin Testing ................................................................... 15

4.1.5

Gaussian Noise Immunity Testing.......................................................... 15

4.1.6

60 Hz Pulse Modulation Immunity Testing ............................................. 15

4.1.7

Receiver Timing Recovery Testing ........................................................ 15

5.0

Mechanical Specifications

.................................................................................... 17

Figures

LXT312A/LXT315A Block Diagram ....................................................................... 5

LXT312A/LXT315A Pin Assignments and Package Markings .............................. 6

Typical T1 Dual Repeater/Transceiver Application ............................................. 11

Alternate Timing Reference Circuitry .................................................................. 11

Digital Timing Characteristics.............................................................................. 13

Receiver Jitter Tolerance Template .................................................................... 14

Receiver Jitter Transfer Template ....................................................................... 14

Receiver Jitter Tolerance Test Setup .................................................................. 14

Receiver Jitter Transfer Test Setup.....................................................................14

Receiver Noise Interference Margin Test Setup ................................................. 15

Receiver Gaussian Noise Immunity Test Setup ..................................................16

Receiver 60 Hz Pulse Amplitude Modulation Immunity Test Setup .................... 16

Receiver Timing Recovery Phase Shift Modulation Test Setup.......................... 16

LXT312NE / LXT315NE Package Specifications ................................................ 17

LXT312PE / LXT315PE Package Specifications ................................................ 18

LXT312A/LXT315A -- Low Power T1 PCM Repeaters/Transceivers

Datasheet

1.0

Pin Assignments and Signal Descriptions

Figure 2. LXT312A/LXT315A Pin Assignments and Package Markings

LXT312NE

LXT315NE

GNDR

RTIP2

2
3
4
5
6
7

RRING2
LPBK
XTO
XTI
TTIP2
TRING2

15
14
13
12
11
10

RTIP1

RRING1

VCC

RCLK1

TTIP1

RCLK2

TRING1

GNDT

GNDR

N/C

2
3
4
5
6
7

N/C
LPBK
XTO
XTI
N/C
N/C

15
14
13
12
11
10

RTIP1

RRING1

VCC

RCLK1

TTIP1

N/C

TRING1

GNDT

8
9
10
11
12
13
14

N/C
N/C
N/C
N/C

N/C

N/C
N/C
N/C
N/C
N/C

N/C

VCC

I
N

I
P

RRING2

PBK

N/C

N/C
N/C
N/C
N/C

N/C

39
38
37
36
35
34
33
32

N/C
N/C
N/C

31
30
29

15
16

N/C

RCL

IP1

TRING

GNDT

IP2

XTI

N/C

8
9
10
11
12
13
14

N/C
N/C
N/C
N/C

N/C

N/C
N/C
N/C
N/C
N/C

N/C

RCL

VCC

RRING1

RTIP1

GNDR

N/C

LPBK

N/C

N/C
N/C
N/C
N/C

N/C

39
38
37
36
35
34
33
32

N/C
N/C
N/C

31
30
29

15
16

TTIP1

TRI

NDT

XTI

XTO

LXT312PE XX
XXXXXX
XXXXXXXX

Part #

LOT #

FPO #

LXT315PE XX
XXXXXX
XXXXXXXX

Part #

LOT #

FPO #

312NE

XXX

315NE

XXX

Low Power T1 PCM Repeaters/Transceivers -- LXT312A/LXT315A

Datasheet

Package Topside Markings

Marking

Definition

Part #

Unique identifier for this product family.

Rev #

Identifies the particular silicon "stepping" -- refer to the specification update for additional stepping information.

Lot #

Identifies the batch.

FPO #

Identifies the Finish Process Order.

Table 1. LXT 312A / LXT315A Signal Descriptions

Pin #

Symbol

I/O

Description

PDIP

PLCC

RTIP1

RRING1

Repeater Tip and Ring Inputs. Tip and ring receive inputs for Channel 1.

RCLK1

Recovered Clock. Clock output recovered from Channel 1 receive input.

TTIP1

TRING1

Repeater Tip and Ring Outputs. Open-drain output drivers for Channel 1.

XTI

XTO

Crystal Oscillator Pins. A 6.176 MHz crystal should be connected across these two
pins. For alternative timing references, refer to Application Information.

VCC

Power Supply. Power supply input for all circuits. +5 V (±0.25 V).

GNDT

GNDR

Transmit Ground. Ground return for transmit circuits.

Receive Ground. Ground return for receive circuits.

TRING2

TTIP2

Side 2 Ring and Tip Outputs. On the LXT312A dual repeater/transceiver, these are
open-drain output drivers for Channel 2.

RRING2

RTIP2

Side 2 Ring and Tip Inputs. On the LXT312A repeater/transceiver, these are tip and
ring receive inputs for Channel 2.

RCLK2

Recovered Clock. On the LXT312A dual repeater/transceiver, this is the recovered
clock output for Channel 2.

LPBK

Loopback Control. On the LXT312A, this pin controls Loopback Selection:

High = Loopback side 1 data to side 2. Low = No Loopback.

On LXT315A single repeater/transceiver, this pin must be connected to GND.

1. On the LXT315NE and LXT315PE single repeater/transceiver, these pins are not connected (N/C).
2. On the LXT312PE and LXT315PE, pins 5 through 18 and 27 through 40 are not connected (N/C).

Figure 2. LXT312A/LXT315A Pin Assignments and Package Markings

LXT312A/LXT315A -- Low Power T1 PCM Repeaters/Transceivers

Datasheet

2.0

Functional Description

2.1

Introduction

PCM signals are attenuated and dispersed in time as they travel down a transmission line.
Repeaters/transceivers are required to amplify, reshape, regenerate, and retime the PCM signal,
then retransmit it.

The LXT312A and LXT315A each contain all the circuits required to build a complete PCM
repeater/transceiver. The operational range of the repeaters/transceivers is 0 to 36 dB of cable loss
at 772 kHz (equal to 6300 feet of 22 gauge pulp-insulated cable between repeaters).

2.2

Receive Function

The signal is received through a 1:1 transformer at RTIP and RRING and equalized for up to 36 dB
of cable loss. The receive equalizer uses a proprietary on-chip adaptive filter technique which is
equivalent to a 3-port ALBO equalizer design. The monolithic structure of the filter and the
absence of external components provide excellent ISI and dispersion elimination, and accurate data
transfer over temperature.

Receiver noise immunity is optimized by a proprietary crosstalk elimination filter which eliminates
the unnecessary high-frequency components of the received signal.

2.2.1

Timing Recovery Function

The equalized signal is full wave rectified and used to generate information for the timing recovery
circuit. This circuit uses a mixed analog/digital technique to provide a low-jitter PLL similar to a
tuned tank with excellent jitter tracking ability. But unlike a tuned tank, the free running frequency
of the PLL clock is accurately controlled by the external reference crystal. No adjustment is
required. Refer to

Table 2

for crystal specifications.

Recovered clock signals are available on the RCLK pins for applications that require bit stream
synchronization.

2.3

Transmit Function

Recovered data is re-synchronized to the recovered clock signal by the timing recovery and
transmit control section. The data is then retransmitted to the network via two open-drain, high-
voltage transistors.

LXT312A/LXT315A -- Low Power T1 PCM Repeaters/Transceivers

Datasheet

3.0

Application Information

3.1

Introduction

Figure 3

shows a typical T1 dual repeater/transceiver application using an LXT312A repeater/

transceiver with standard PCB edge connectors. It includes a jumper-selectable shorting option
(dashed lines at connector pins 2 and 7) for the fault location circuitry.

Table 2

lists the

specifications for the crystal used with the LXT312A or LXT315A repeater.

3.1.1

Alternate Timing Reference

For applications where a crystal is not appropriate, a 1.544 MHz or 6.176 MHz, CMOS-level (High

4.5V, Low

0.5V) oscillator may be connected to XTI. In this situation, XTO must be tied to

VCC and GND via a voltage divider as shown in

Figure 4

Table 2. Crystal Specifications

Parameter

Specification

Frequency

6.176 MHz

Frequency tolerance

± 50 ppm

Effective series resistance

Maximum

Crystal cut

Resonance

Parallel

Maximum drive level

2.0 mW

Mode of operation

Fundamental

1. @ 25 °C, C Load = 10 pF; and from -40 °C to +85 °C

(Ref 25 °C reading).

Low Power T1 PCM Repeaters/Transceivers -- LXT312A/LXT315A

Datasheet

Figure 3. Typical T1 Dual Repeater/Transceiver Application

Figure 4. Alternate Timing Reference Circuitry

NOTES:

RTIP/RRING Resistors are used to provide surge protection. Values can be 0 100

** TTIP/TRING Zeners are used to reduce surge susceptibility. Values can be 12 14 V.

5.6

SCHOTT
#10951

100

1ct : 1

RTIP1

RRING1

VCC

RCLK1

RCLK2

TTIP1

TRING1

GNDT

GNDR

RTIP2

RRING2

LPBK

XTO

XTI

TTIP2

TRING2

5.6

SCHOTT
#10951

100

1 : 1ct

RCV2

RCV1

LXT312

1 µF

SCHOTT
#12535-9027

3ct : 1 : 1ct

6.3 V

XMT2

5.6

240

5.1 V

SCHOTT
#12535-9027

1 : 1ct : 3ct

XMT1

5.6

240

100 µH

100 µF

0.1 µF

6.176 MHz

100 µH

2 k

3 k

Vcc

XTO

XTI

LXT312A

Oscillator

(See Note 1)

CMOS-level Input

1. Oscillator drive levels:

High S 4.5 V
Low £ 0.5 V

LXT312A/LXT315A -- Low Power T1 PCM Repeaters/Transceivers

Datasheet

4.0

Test Specifications

Note:

Minimum and maximum values in

Table 3

through

Table 6

and

Figure 5

through

Figure 13

represent the performance specifications of the LXT312A/315A repeaters/transceivers and are
guaranteed by test except, as noted, by design.

Table 3. Absolute Maximum Ratings

Parameter

Symbol

Unit

Supply voltage (min to max)

-0.3 V to +6 V

Driver voltage

18 V

Receiver current

100 mA

Operating temperature (min to max)

-40 °C to +85 °C

Storage temperature (min to max)

-65 °C to +150 °C

Caution: Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied.

Exposure to maximum rating conditions for extended periods may affect device reliability.

Table 4. Recommended Operating Conditions

Parameter

Symbol

Min

Typ

Max

Unit

Supply voltage

4.75

5.0

5.25

Operating temperature

-40

° C

Table 5. Electrical Characteristics (Over Recommended Range)

Parameter

Symbol

Min

Typ

Max

Unit

Interference margin

SNR

-11

Receiver dynamic range

-36

Digital outputs - low

= 1.6 mA

0.4

= 10

0.2

Digital outputs - high

= 0.4 mA

2.4

< 10

4.5

Digital inputs - high

2.0

Digital inputs - low

0.8

Supply current (from VCC supply)

All zeros

All ones

Driver leakage current (V

DVR

= 18 V)

150

Driver pulse amplitude (Driver output I

= 20 mA)

0.65

0.95

1. Typical values are at 25° C and are for design aid only; they are not guaranteed and not subject to production testing.
2. Measured with C

LOAD

10 pF, R

LOAD

> 100 k

Low Power T1 PCM Repeaters/Transceivers -- LXT312A/LXT315A

Datasheet

4.1

Test Setups

4.1.1

Introduction

Both the LXT312A and LXT315A are fully tested (100% AC and DC parameters) using inputs
generated by Intel's proprietary transmission line and network simulator. Device testing includes
receiver jitter tolerance, jitter transfer and interference margin, and receiver immunity to Gaussian
and 60 Hz noise. Specifications and bench test setups are shown in

Figure 6

through

Figure 13

4.1.2

Receiver Jitter Tolerance Testing

Receiver jitter tolerance meets the template shown in

Figure 6

, when operated at line losses from 0

to 36 dB.

Figure 8

shows the setup used for jitter tolerance testing.

4.1.3

Receiver Jitter Transfer Testing

Receiver jitter transfer meets the template shown in

Figure 7

, when operated with line losses from

0 to 36 dB and input jitter amplitude of 0.15 UI peak-to-peak. Jitter gain at a given frequency is
defined as the difference between intrinsic jitter and additive jitter at the measurement frequency,
divided by the amplitude of the input jitter.

Figure 9

shows the setup used for jitter transfer testing.

Figure 5. Digital Timing Characteristics

Table 6. Digital Timing Characteristics (Over Recommended Range)

Parameter

Symbol

Min

Typ

Max

Unit

Driver pulse width

299

324

349

Driver pulse imbalance

Rise and fall time (any digital output

)

Setup time - TTIP/TRING to RCLK

TSU

Hold time - TTIP/TRING from RCLK

1. Typical values are at 25° C and are for design aid only; they are not guaranteed and not subject to production testing.
2. Measured with C

LOAD

10 pF, R

LOAD

> 100 k

RCLK

TTIP,
TRIN

(with external pull-up)

TSU

LXT312A/LXT315A -- Low Power T1 PCM Repeaters/Transceivers

Datasheet

Figure 6. Receiver Jitter Tolerance Template

Figure 7. Receiver Jitter Transfer Template

Figure 8. Receiver Jitter Tolerance Test Setup

Figure 9. Receiver Jitter Transfer Test Setup

10 Hz

6430 Hz

40 kHz

Jitter Frequency

Sinus

dal

I
nput

i
t
t
er A

plit

ude

(Pk

)

0.3
UI

-20 dB/Decade Slope

Acceptable Range

9650

Jitter Frequency (Hz)

i
tt

r
Ga

(

)

0.1

-20 dB/Decade
Slope

Acceptable Range

QRSS

Source with

Zero

Restriction

Sinusoidal

Jitter

Modulator

Cable

0 dB to 36 dB

@ 772 kHz

LXT312A/

LXT315A

Repeater/

Transceiver

Error

Detector

QRSS

Source with

Zero

Restriction

Sinusoidal

Jitter

Modulator

Cable

0 dB to 36 dB

@ 772 kHz

LXT312A/

LXT315A

Repeater/

Transceiver

Jitter

Demodulator

Spectrum

Analyzer

Low Power T1 PCM Repeaters/Transceivers -- LXT312A/LXT315A

Datasheet

4.1.4

Interference Margin Testing

The LXT312A and LXT315A receiver noise interference margin is specified at a minimum of -11
dB for line losses from 0 dB to 36 dB. The test setup used to measure noise margin is shown in

Figure 10

4.1.5

Gaussian Noise Immunity Testing

Receiver immunity to Gaussian noise is specified at a maximum BER of 10

-7

for a quasi-random

T1 signal at 1.544 MHz (

130 ppm). The receiver must be immune to noise power expressed as Np

= -(L + 4.7) dBm, where L corresponds to the line loss and is valid for 0 to 36 dB.

Figure 11

shows the setup used to test Gaussian noise immunity. The noise source is Gaussian to at

least 6 sigma and filtered to simulate expected noise in a binder group (per AT&T TA #24/CB113).

4.1.6

60 Hz Pulse Modulation Immunity Testing

Receiver immunity to 60 Hz pulse amplitude modulation is specified using the Gaussian noise
source described in the previous paragraph on Gaussian noise immunity. Pulse amplitude
modulation is specified between 10% and 30% of the nominal amplitude (see AT&T TA #24/
CB113 for details on the modulation envelope).

Figure 12

shows the setup used for testing receiver

immunity to 60 Hz pulse amplitude modulation. The following data reflect noise power for 10

-7

BER at each modulation level, where L corresponds to the line loss and is valid for 0 to 36 dB:

Modulation Level

Noise Power

10%

Np = -(L + 5.7) dBm

20%

Np = -(L + 6.7) dBm

30%

Np = -(L + 8.7) dBm

4.1.7

Receiver Timing Recovery Testing

Receiver timing recovery phase shift modulation for repetitive 8-bit patterns is specified at less
than 0.07 UI. This is tested using any two out of 35 possible 8-bit patterns and measuring the
change in output pulse timing from one pattern to the other (see AT&T TA #24/CB113 for details
on the patterns). The switching rate from one pattern to the other is specified at between 300 Hz
and 500 Hz. The setup used to test receiver timing recovery phase shift modulation is shown in

Figure 13

Figure 10. Receiver Noise Interference Margin Test Setup

QRSS Source

with Artificial Line

Interference Generator

and Error Detector

LXT312A/

LXT315A

Repeater/

Transceiver

(Lear Siegler 415A-2 or Equivalent)

Line Out

Line In

LXT312A/LXT315A -- Low Power T1 PCM Repeaters/Transceivers

Datasheet

Figure 11. Receiver Gaussian Noise Immunity Test Setup

Figure 12. Receiver 60 Hz Pulse Amplitude Modulation Immunity Test Setup

Figure 13. Receiver Timing Recovery Phase Shift Modulation Test Setup

QRSS

Source with

Zero

Restriction

Cable

0 dB to 36 dB

@ 772 kHz

LXT312A/

LXT315A

Repeater/

Transceiver

Error

Detector

Gaussian

White Noise

Generator

Filter

Compatible

with TA #24

QRSS

Source with

Zero

Restriction

Cable

0 dB to 36 dB

@ 772 kHz

LXT312A/

LXT315A

Repeater/

Transceiver

Error

Detector

Gaussian

White Noise

Generator

Filter

Compatible

with TA #24

60 Hz

Amplitude
Modulator

Pattern

Setting

Cable

0 dB to 36 dB

@ 772 kHz

LXT312A/

LXT315A

Repeater/

Transceiver

Pattern

Switching

Control

Transmitter

Pattern

Setting

Phase

Shift

Measuring

Low Power T1 PCM Repeaters/Transceivers -- LXT312A/LXT315A

Datasheet

5.0

Mechanical Specifications

Figure 14. LXT312NE / LXT315NE Package Specifications

16-Pin Plastic Dual In-Line Package

Part Number LXT312NE & LXT315NE

Extended Temperature Range (-40

C to +85

Dim

Inches

Millimeters

Min

Max

Min

Max

0.210

5.334

0.115

0.195

2.921

4.953

0.014

0.022

0.356

0.559

0.045

0.070

1.143

1.778

0.030

0.045

0.762

1.143

0.735

0.775

18.669

19.685

0.300

0.325

7.620

8.255

0.240

0.280

6.096

7.112

0.100 BSC (Nominal)

2.540 BSC (Nominal)

0.300 BSC (Nominal)

7.620 BSC (Nominal)

0.430

10.922

0.115

0.150

2.921

3.810

1. BSC: Basic Spacing between Centers

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: LXT312A

Document Outline

Ð­Ð»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: LXT312A

Document Outline

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: LXT312A