DC2063A - ANALOG DEVICES - Datasheet.Directory

dc2063af

DEMO MANUAL DC2063A

Description

LTC2875

±60V Fault Protected 3.3V or 5V

High Speed CAN Transceiver

Demonstration circuit 2063A is a robust high speed, low

power, ISO 11898-2 compliant CAN transceiver featuring

the LT C

2875. The demo circuit operates on 3.3V or 5V

supplies and features ±60V overvoltage fault protection on

the data transmission lines during all modes of operation.

The demo circuit contains all the components necessary

to demonstrate the features of the LTC2875 in a CAN

network, including a terminated SMB jack for TXD data

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear

Technology Corporation. All other trademarks are the property of their respective owners.

performance summary

operating principles

input, jumper selectable CAN bus termination (supporting

either single or split termination configurations), and a

jumper selectable variable slew rate control.

Design files for this circuit board are available at

http://www.linear.com/demo/DC2063A

Specifications are at TA = 25°C

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

VCC Input Supply Range 3.3V VCC Range 3.0 3.3 3.6 V

5V VCC Range 4.5 5.0 5.5 V

fMAX Maximum Data Rate JP3 in ‘MAX’ position 4 Mbps

Interface I/O: CANH, CANL –60 60 V

Bus Differential Voltage (CANH-CANL) JP2 in ‘SINGLE’ or ‘SPLIT’ position 10 V

The LTC2875 is enabled by pulling the RS pin low. The

slew rate of the transmitter can be controlled by pulling RS

low with a resistor ≤ 200kΩ, with the slew rate decreasing

with increasing resistor value. The DC2063A provides two

jumper positions to enable the LTC2875. With a jumper

in the JP3:MAX position, the RS pin is grounded and the

LTC2875 operates at its maximum slew rate. With a jumper

in the JP3:ADJ position, the transmitter slew rate can be

varied from its minimum to maximum using 200kΩ vari-

able resistor RV1. When no jumper is placed on JP3, the

RS pin in the LTC2875 is pulled up by an internal 250kΩ

resistor, putting the chip in the shut-down state.

The data input signal can be applied to the LTC2875 TXD pin

through either the TXD turret or the SMB jack J1. To apply

the TXD signal through the SMB jack J1, place a jumper

on the JP1:SMB position. The SMB input is terminated to

GND by a 50Ω resistor. To apply the TXD signal through the

TXD turret, place a jumper on the JP1:TURRET position.

The TXD turret input contains a 100Ω series resistor but is

not terminated. Jumpers may be applied to both JP1:SMB

and JP1:TURRET to enable applying a signal from a pulse

generator through the SMB jack J1 and monitoring the

signal with a scope probe on the TXD turret.

dc2063af

DEMO MANUAL DC2063A

Quick start proceDure

operating principles

Demonstration circuit 2063A is easy to set up and evaluate

the performance of the LTC2875.

1. Verify the jumpers are in the following default positions:

JP1:SMB ON; JP1:TURRET OFF

JP2: SPLIT

JP3:MAX ON; JP3:ADJ OFF

2. With power off, connect the input power supply to VCC

and GND turrets.

3. Turn on the power at the input.

When TXD is low, the LTC2875 drives the dominant state

onto the CANH and CANL bus lines, with CANH pulled high

and CANL pulled low. When TXD is high, the LTC2875 is

in the recessive state, with both CANH and CANL drivers

in the high impedance state, and the differential voltage on

the CAN bus lines is returned to near zero by the termina-

tion resistors. The TXD pin is pulled high by an internal

500kΩ resistor when it is left floating.

The CAN bus must be terminated at both ends by resis-

tors matched to the impedance of the bus cable, typically

120Ω, while all other nodes on the CAN bus must be

unterminated. The DC2063A provides three jumper select-

able termination configurations: split termination, single

termination, and no termination. The split termination

is selected by placing two jumpers on JP2 in the SPLIT

(vertical) configuration. This provides 120Ω termination

consisting of two series 60Ω resistors with the LTC2875

SPLIT pin and a 4.7nF decoupling capacitor biasing the

termination center point. This configuration lowers the

EME of the transmitted signal by reducing common mode

voltage fluctuations. The single termination is selected by

placing two jumpers on JP2 in the SINGLE (horizontal)

configuration. This provides 120Ω termination consisting

of two series 60Ω resistors with no biasing of the center

point. No termination may be selected by removing both

jumpers from JP2.

The LTC2875 receiver senses the differential voltage on

the CAN bus lines and produces a digital output on the

RXD pin. When a dominant state is sensed on the bus

lines, the RXD output will pull low. When a recessive state

is sensed on the bus lines, the RXD output will pull high.

When the LTC2875 is in the shutdown state, the RXD pin

is pulled high by an internal 500kΩ resistor. The LTC2875

RXD pin is connected directly to the DC2063A RXD turret.

NOTE: Make sure the input voltage does not exceed 6V.

4. Connect a function generator to SMB jack J1 and set

to square wave with a low of 0V, high = VCC. Set fre-

quency to 100kHz (200kbps). Enable output of function

generator.

5. Connect oscilloscope to pin RXD and observe 100kHz

waveform. This demonstration shows that data applied

to TXD is transmitted to the CAN bus, looped back

through the receiver, and outputted on RXD.

dc2063af

DEMO MANUAL DC2063A

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-

tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

parts list

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER

Required Circuit Components

1 1 U1 IC, CAN Transceiver LINEAR LTC2875IDD

Hardware/Components (For Demo Board Only)

2 1 C1 Capacitor, 2.2µF, 10%, 0603, 10V, X7R Murata/GRM188R71A225KE15D

3 1 C2 Capacitor, 4700pF 20% 0603, 100V, X7R AVX/06031C472MAT2A

4 1 C3 Capacitor, Tantalum, 6.8µF, 10%, 3216, 16V AVX/TAJA685K016RNJ

5 2 E1, E2 Turret Mill Max/2308-2-00-80-00-00-07-0

6 2 E3, E4 Turret Mill Max/2501-2-00-80-00-00-07-0

7 1 J1 Connector, SMB Male Jack, Straight, 50Ω Amphenol/142138

8 1 J2 Terminal Block, 3 Position, Side Entry 3.5mm TE Connectivity/284391-3

9 3 JP1-3 Header, 2 x 2 0.1" Samtec/TSW-102-07-G-D

10 1 R1 Resistor, 49.9Ω, 1%, 1210 Panasonic/ERJ-14NF49R9U

11 1 R2 Resistor, 100Ω, 5%, 1206 AAC/CR10-101JM

12 2 R3, R4 Resistor 60.4Ω, 1%, 1210 Vishay/CRCW121060R4FKEA

13 1 RV1 Trimmer, 200kΩ, 1-Turn Panasonic/EVM-3VSX50B25

14 4 Standoff, Snap-on Keystone/8833

schematic Diagram

dc2063af

DEMO MANUAL DC2063A

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com

 LINEAR TECHNOLOGY CORPORATION 2014

LT 1014 • PRINTED IN USA

DEMONSTRATION BOARD IMPORTANT NOTICE

Linear Technology Corporation (LT C ) provides the enclosed product(s) under the following AS IS conditions:

This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT

OR EVALUATION PURPOSES ONLY and is not provided by LT C for commercial use. As such, the DEMO BOARD herein may not be complete

in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety

measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union

directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.

If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date

of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU

OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS

FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR

ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.

The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LT C from all claims

arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all

appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or

agency certified (FCC, UL, CE, etc.).

No License is granted under any patent right or other intellectual property whatsoever. LT C assumes no liability for applications assistance,

customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.

LT C currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.

Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and

observe good laboratory practice standards. Common sense is encouraged.

This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LT C applica-

tion engineer.

Mailing Address:

Linear Technology

1630 McCarthy Blvd.

Milpitas, CA 95035