SN65HVD251 - in case of total load under 45ohm

Hirotaka Matsumoto

Hi all,

We have a question as following;

We have the reply from you as following;
"For the CAN transceiver, the total load can exceed 60 Ohm, it is reasonable if the total load is between 45 Ohm and 65 Ohm."
Please refer to "http://e2e.ti.com/support/interface/industrial_interface/f/142/p/403178/1430042#1430042".

If total load is less than 45ohm, what kind of problem will be happened?
-FC will increases,
-Consumption current increases, so device will be hotter
-Cable impedance miss-match will be occurred, so reflection will be occurred

If you have some information, could you let us know?

Kind regards,

Hirotaka Matsumoto

over 11 years ago

0 Michael Peffers over 11 years ago

TI__Mastermind 20820 points

Hi Hirotaka,

The ISO 11898 standard sets the limits of the CAN termination value to be between 45 and 65 ohms. Of course a design can deviate from this if the desired performance is of the system is meet but CAN transceivers are design to work within the limits reference above. The below link leads to a short wiki about CAN temination techniques:

-FC will increases

The cut off frequency calculation is discussed in the provided wiki.
-Consumption current increases, so device will be hotter

I am not sure about this, we have no data to support this claim.
-Cable impedance miss-match will be occurred, so reflection will be occurred.

Absolutely, the termination impedance needs to be balance with the media impedance to ensure no SI issues.

Please let me know what other questions you have.

0 Hirotaka Matsumoto over 11 years ago in reply to Michael Peffers

Guru 27595 points

Michael san,

Thank you for your reply.

Kind regards,

Hirotaka Matsumoto

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SN65HVD251 - in case of total load under 45ohm