SLLS933G November   2008  – January 2015 SN65HVD233-HT

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (Continued)
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  Recommended Operating Conditions
    4. 7.4  Thermal Information
    5. 7.5  Driver Electrical Characteristics
    6. 7.6  Receiver Electrical Characteristics
    7. 7.7  Driver Switching Characteristics
    8. 7.8  Receiver Switching Characteristics
    9. 7.9  Device Switching Characteristics
    10. 7.10 Typical Characteristics
  8. 8 Parameter Measurement Information
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 ISO 11898 Compliance of SN65HVD23x Family of 3.3-V CAN Transceivers
        1. 9.3.1.1 Differential Signal
          1. 9.3.1.1.1 Common-Mode Signal
        2. 9.3.1.2 Interoperability Of 3.3-V CAN in 5-V CAN Systems
    4. 9.4 Device Functional Modes
      1. 9.4.1 Function Tables
      2. 9.4.2 Equivalent Input and Output Schematic Diagrams
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Diagnostic Loopback
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Slope Control
        2. 10.2.2.2 Standby
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Trademarks
    2. 13.2 Electrostatic Discharge Caution
    3. 13.3 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

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9 Detailed Description

9.1 Overview

Controller Area Network (CAN) is a robust multi master-master, differential signaling, serial communications bus specified by the ISO 11898 family of standards. TI's SSN65HVD23x family of transceivers solve specialized networking requirements for various applications.

Table 2. Available Options

ORDERABLE PART NUMBER LOW-POWER MODE SLOPE
CONTROL		 DIAGNOSTIC
LOOPBACK		 AUTOBAUD
LOOPBACK
SN65HVD233HD 200-μA standby mode Adjustable Yes No
SN65HVD233SJD
SN65HVD233SKGDA
SN65HVD233SHKJ
SN65HVD233SHKQ

9.2 Functional Block Diagram

fun_blk_lls557.gif

9.3 Feature Description

9.3.1 ISO 11898 Compliance of SN65HVD23x Family of 3.3-V CAN Transceivers

Many users value the low power consumption of operating CAN transceivers from a 3.3-V supply. However, some are concerned about the interoperability with 5-V supplied transceivers on the same bus. This section analyzes this situation to address those concerns.

9.3.1.1 Differential Signal

CAN is a differential bus where complementary signals are sent over two wires, and the voltage difference between the two wires defines the logical state of the bus. The differential CAN receiver monitors this voltage difference and outputs the bus state with a single-ended output signal.

diff_pov_wf_lls557.gifFigure 26. Typical SN65HVD23x Differential Output Voltage Waveform

The CAN driver creates the difference voltage between CANH and CANL in the dominant state. The dominant differential output of the SN65HVD23x is greater than 1.5 V and less than 3 V across a 60-Ω load. The minimum required by ISO 11898 is 1.5 V and the maximum is 3 V. These are the same limiting values for 5-V supplied CAN transceivers. The bus termination resistors drive the recessive bus state and not the CAN driver.

A CAN receiver is required to output a recessive state with less than 500 mV and a dominant state with more than 900-mV difference voltage on its bus inputs. The CAN receiver must do this with common-mode input voltages from –2 V to 7 V. The SN65HVD23x family receivers meet these same input specifications as 5-V supplied receivers.

9.3.1.1.1 Common-Mode Signal

A common-mode signal is an average voltage of the two signal wires that the differential receiver rejects. The common-mode signal comes from the CAN driver, ground noise, and coupled bus noise. Obviously, the supply voltage of the CAN transceiver has nothing to do with noise. The SN65HVD23x family driver lowers the common-mode output in a dominant bit by a couple hundred millivolts from that of most 5-V drivers. While this does not fully comply with ISO 11898, this small variation in the driver common-mode output is rejected by differential receivers and does not affect data, signal noise margins, or error rates.

9.3.1.2 Interoperability Of 3.3-V CAN in 5-V CAN Systems

The 3.3-V–supplied SN65HVD23x family of CAN transceivers are electrically interchangeable with 5-V CAN transceivers. The differential output is the same. The recessive common-mode output is the same. The dominant common-mode output voltage is a couple hundred millivolts lower than 5-V–supplied drivers, while the receivers exhibit identical specifications as 5-V devices.

Electrical interoperability does not assure interchangeability however. Most implementers of CAN buses recognize that ISO 11898 does not sufficiently specify the electrical layer and that strict standard compliance alone does not ensure interchangeability. This comes only with thorough equipment testing.

9.4 Device Functional Modes

9.4.1 Function Tables

Table 3. Function Table (Driver)(1)

DRIVER
INPUTS OUTPUTS
D LBK Rs CANH CANL BUS STATE
X X >0.75 VCC Z Z Recessive
L L or open ≤0.33 VCC H L Dominant
H or open X Z Z Recessive
X H ≤0.33 VCC Z Z Recessive

Table 4. Function Table (Receiver)

RECEIVER
INPUTS OUTPUT
BUS STATE VID = V(CANH) – V(CANL) LBK D R
Dominant VID ≥ 0.9 V L or open X L
Recessive VID ≤ 0.5 V or open L or open H or open H
? 0.5 V < VID < 0.9 V L or open H or open
X X H L L
X X H H
(1) H = high level, L = low level, Z = high impedance, X = irrelevant, ? = indeterminate

9.4.2 Equivalent Input and Output Schematic Diagrams

sch_01_diag_lls557.gifFigure 27. D Input
sch_03_diag_lls557.gifFigure 29. CANH Input
sch_05_diag_lls557.gifFigure 31. CANH and CANL Outputs
sch_07_diag_lls557.gifFigure 33. LBK Input
sch_02_diag_lls557.gifFigure 28. RS Input
sch_04_diag_lls557.gifFigure 30. CANL Input
sch_06_diag_lls557.gifFigure 32. R Output