SN65HVD234: triple termination - how bad is it?

Di Hu

Part Number: SN65HVD234

Tool/software:

Typically we should have two 120 Ohm termination for the CAN interface at the end points of the CAN network. What we found was the previous design had a total of 3x 120 Ohm termination. Can you please let me know what damage this would do to the CAN transceiver? Is the output current out of spec in this situation?

3 months ago

0 Clemens Ladisch 3 months ago

Guru 316780 points

The outputs can handle a load of 40 Ω, but the voltage drop over the termination might not longer meet the specified minimum of 1.2 V.

0 Di Hu 3 months ago in reply to Clemens Ladisch

Prodigy 40 points

Will this damage the SN65HVD234 part?

0 Clemens Ladisch 3 months ago in reply to Di Hu

Guru 316780 points

It would result in a power dissipation of roughly 100 mW. See section 8.5; the ambient temperature must not be too high.

0 Ethan Sempsrott 3 months ago in reply to Di Hu

TI__Genius 13662 points

Hi Di,

3 nodes with 120 Ohm termination is not recommended as you know. The main issue I see is that it will likely prevent valid dominant voltages so communication will be impaired.

As for damage, this will not immediately damage the device, but as Clemens mentioned, if power dissipation creates too much heat, it could violate the junction/ambient temperature absolute max.

I would recommend looking into this reference design which can be used to create selectable termination for a CAN node: https://www.ti.com/lit/ug/tiducf3/tiducf3.pdf

Best,

Ethan

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SN65HVD234: triple termination - how bad is it?