ns32491a National Semiconductor Corporation, ns32491a Datasheet

ns32491a

Manufacturer Part Number

ns32491a

Description

Sni Serial Network Interface

Manufacturer

National Semiconductor Corporation

Datasheet

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C 1995 National Semiconductor Corporation

DP8391A NS32491A SNI Serial Network Interface

General Description

The DP8391A Serial Network Interface (SNI) provides the

Manchester data encoding and decoding functions for

IEEE 802 3 Ethernet Cheapernet type local area networks

The SNI interfaces the DP8390 Network Interface Controller

(NIC) to the Ethernet transceiver cable When transmitting

the SNI converts non-return-to-zero (NRZ) data from the

controller and clock pulses into Manchester encoding and

sends the converted data differentially to the transceiver

The opposite process occurs on the receive path where a

digital phase-locked loop decodes 10 Mbit s signals with as

much as

The DP8391A SNI is a functionally complete Manchester

encoder decoder including ECL like balanced driver and re-

ceivers on board crystal oscillator collision signal transla-

tor and a diagnostic loopback circuit

The SNI is part of a three chip set that implements the com-

plete IEEE compatible network node electronics as shown

below The other two chips are the DP8392 Coax Transceiv-

er Interface (CTI) and the DP8390 Network Interface Con-

troller (NIC)

Incorporated into the CTI are the transceiver collision and

jabber functions The Media Access Protocol and the buffer

management tasks are performed by the NIC There is an

isolation requirement on signal and power lines between the

CTI and the SNI This is usually accomplished by using a set

of miniature pulse transformers that come in a 16-pin plastic

DIP for signal lines Power isolation however is done by

using a DC to DC converter

Features

1 0 System Diagram

Compatible with Ethernet II

10Base2 and 10Base-T

18 ns of jitter

IEEE 802 3 Compatible Ethernet Cheapernet Local Area Network Chip Set

TL F 9357

IEEE 802 3

10Base5

Table of Contents

1 0 System Diagram

2 0 Block Diagram

3 0 Functional Description

3 1

3 2

3 3

3 4

3 5

4 0 Connection Diagrams

5 0 Pin Descriptions

6 0 Absolute Maximum Ratings

7 0 Electrical Characteristics

8 0 Switching Characteristics

9 0 Timing and Load Diagrams

10 0 Physical Dimensions

10 Mb s Manchester encoding decoding with receive

clock recovery

Patented digital phase locked loop (DPLL) decoder re-

quires no precision external components

Decodes Manchester data with up to

Loopback capability for diagnostics

Externally selectable half or full step modes of opera-

tion at transmit output

Squelch circuits at the receive and collision inputs re-

ject noise

High voltage protection at transceiver interface (16V)

TTL MOS compatible controller interface

Connects directly to the transceiver (AUI) cable

Oscillator

Encoder

Decoder

Collision Translator

Loopback

RRD-B30M105 Printed in U S A

18 ns of jitter

TL F 9357 – 1

July 1993

Related parts for ns32491a

ns32491a Summary of contents

Page 1

... DP8391A NS32491A SNI Serial Network Interface General Description The DP8391A Serial Network Interface (SNI) provides the Manchester data encoding and decoding functions for IEEE 802 3 Ethernet Cheapernet type local area networks The SNI interfaces the DP8390 Network Interface Controller (NIC) to the Ethernet transceiver cable When transmitting ...

Page 2

Block Diagram 3 0 Functional Description The SNI consists of five main logical blocks a) the oscillator generates the 10 MHz transmit clock sig- nal for system timing b) the Manchester encoder and differential output driver accepts NRZ ...

Page 3

Functional Description mains high transmit data (TXD) is encoded out to the trans- mit-driver pair ( The transmit enable and transmit data inputs must meet the setup and hold time requirements with respect to the rising ...

Page 4

PCC Connection Diagram Refer to the Oscillator section FIGURE 3b Order Number DP8391AV NS Package Number V28A 9357 – 5 ...

Page 5

Pin Descriptions Pin No Name I O (DIP) (PCC COL RXD CRS RXC SEL – 9 GND 7 10 LBK I ...

Page 6

Absolute Maximum Ratings Supply Voltage ( Input Voltage (TTL) Input Voltage (differential) Output Voltage (differential) Output Current (differential) Storage Temperature Lead Temperature (soldering 10 sec) Package Power Rating for DIP (PC Board Mounted) ...

Page 7

Switching Characteristics for DIP and for PCC (Note 2) (Continued Symbol Parameter TRANSMIT SPECIFICATION (Continued) t Transmit Output Delay ...

Page 8

Timing and Load Diagrams FIGURE 5 Transmit Timing - End of Transmission (last bit FIGURE 6 Transmit Timing - End of Transmission (last bit (Continued 9357 – 9357 ...

Page 9

Timing and Load Diagrams FIGURE 7 Receive Timing - Start of Packet FIGURE 8 Receive Timing - End of Packet (last bit (Continued 9357 – 9357 – 10 ...

Page 10

Timing and Load Diagrams FIGURE 9 Receive Timing - End of Packet (last bit 27 mH transformer is used for testing purposes 100 mH transformers (Valor LT1101 or Pulse Engineering 64103) are recommended for application use (Continued) e ...

Page 11

Physical Dimensions inches (millimeters) Molded Dual in Line Pkg (N) Order Number DP8391AN NS Package Number N24C 11 ...

Page 12

Physical Dimensions inches (millimeters) (Continued) LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION As used ...

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