Datasheet

75% SAMPLEPOINT

500 mVThreshold

900 mVThreshold

NOISEMARGIN

RECEIVERDETECTIONWINDOW

SN65HVD230

SN65HVD231

SN65HVD232

SLOS346K –MARCH 2001– REVISED FEBRUARY 2011

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Figure 36. Typical SN65HVD230 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 SN65HVD230 is greater than 1.5 V and less than 3 V across a 60-ohm load. The

minimum required by ISO 11898 is 1.5 V and 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 volts. The SN65HVD230 family receivers meet these same input specifications as 5-V

supplied receivers.

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 SN65HVD230 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 effect data, signal noise margins or error rates.

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.

Product Folder Link(s): SN65HVD230 SN65HVD231 SN65HVD232