Propagation Delay and Oscillator Drift Analysis for CAN Networks

For a given CAN application the nominal data rate can be programmed in the range of about 5 Kb/s to 1 Mb/s. Each bit is made up of programmable segments and programmable sampling and synchronization elements. These parameters may be chosen so as to favorably influence the allowed propagation delay through the CAN link and the allowed oscillator frequency tolerance for a CAN node.

This paper will investigate these issues and define several equations that demonstrate the interrelationships of the various CAN bit elements, and the effect that propagation delays and oscillator tolerance have on the fundamental ability of CAN receivers to successfully decode a CAN waveform.

Graphs are given to illustrate the allowable CAN bus length and oscillator tolerance for various bit rates.