TCAN11623-Q1: Load dump profile

Daniel,

I'm not sure I understand the question, are you asking how the TCAN1162x-Q1 responds to a load dump, that is how it is internally protected and if the transient gets clamped? Or something else?

Regards,

Eric Hackett 

Hi Eric,

The customer is looking for a voltage vs time profile like the graph I showed from a competing device.

Are there any additional TCAN1162x-Q1 specs available for load dump definition?

Daniel,

I don't think we have any test data like this available, but I know we have done some ISO 7637 testing on this device which may be similar. I'll share those results with you tomorrow when I find them, thanks for your patience.

Regards,

Eric Hackett 

Hi Eric,

Sounds good, if you could get back to me with these additional test results this would be useful as well

Daniel,

I'm still looking for these test results. I'll get back with you by the end of the week, sorry for the delay and thank you for your patience.

Regards,

Eric Hackett 

Hi Daniel,

Load dump is a test that simulates a relatively long transient voltage on the battery line when the inductive kickback of the starter motor appears on the vehicles supply. The maximum voltage of this transient is generally a bit over 2x the nominal battery voltage and can last for several ms - generally much longer than what most integrated transient suppression mechanisms can handle. Device that are connected to the battery supply are therefore required to be rated for the maximum voltage of the load dump condition as a DC parameter to ensure this does not damage anything. If a device is to be used that has a lower absolute maximum voltage than what the load dump condition requires, external surge protection may be included to clamp the local supply in order to protect the device from the higher voltage of the load dump transient. 

The waveform you shared shows such clamping behavior as I would expect from an external surge diode that would protect a transceiver's battery supply pin from a higher voltage transient. I would not expect any CAN transceiver to be able to integrate this behavior as the power dissipation of such a surge diode generally requires its own package for thermal dissipation. 

For the TCAN1162 itself, it is rated to survive up to 42V on the battery line indefinitely, so any load dump condition that has a maximum voltage equal or less than this value would require no extra protection. If the load dump condition has a maximum voltage larger than this value, external surge protection may be necessary in order to clamp the voltage of the local supply below this 42V absolute maximum rating for the transceiver. 

Do you know what the load dump requirement is for this application? If not, what is the nominal battery supply voltage? We can generally assume that the maximum voltage on the load dump based on the battery voltage in a system. 
What device is the waveform you shared from? Is this from a similar transceiver device or maybe an external clamping passive such as a surge diode? 

Regards, 
Eric Schott