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TCAN1042H: TCAN1042H

Toby Doorn
Prodigy 120 points
Part Number: TCAN1042H
Other Parts Discussed in Thread: SN65HVD1050,
In our system that uses 48V batteries, transient voltage spikes above 100V can occur. In the TCAN1042H datasheet, it is specified that the CANbus pins are fault tolerant up to 70V. Figure 11 in the datasheet shows that ringing can occur for the short circuit test of said pins and that implies that the IC can handle these voltage spikes due to ringing. No magnitude is specified for the ringing voltage however. Also, this blog post (that is referenced on the TCAN1042 product page) suggests that the IC can at least handle voltage spikes up to 120V: https://e2e.ti.com/blogs_/b/analogwire/archive/2018/02/28/transients-in-24v-automobiles   

It is not clear to me what actual voltage spikes the TCAN1042 can handle. Internally, we are having discussions on whether additional protections are required or not. There are suggestions in the documentation that the IC is robust for voltage spikes, but it is not explicitly specified what kind of spikes it can handle above the fault protection level. Is it possible to clarify this spec?

Your help is much appreciated.

Regards,

Toby
  • 0
    TI__Intellectual 2090 points

    Hi Toby,

    Thank you for your question.  I understand the ambiguity for this specification.  Please email me separately at tmmegee@ti.com and I can provide some documentation regarding specific testing that has been employed to test the transient voltage performance on the CAN pins for TCAN1042H.

    Best Regards,

    Max Megee

  • 0 in reply to Max Megee
    Prodigy 120 points
    Hi Max,
    Thanks for the information, we have a couple of follow-up questions.
    Currently we are using the SN65HVD1050 IC. We were looking at the TCAN1042H for its improved robustness. However, the SN65HVD1050 specifies transients according to the ISO7637 standard of +/-200V for all transient pulse types. The TCAN1042H specifies lower voltages for the various transient pulses. Yet the TCAN1042H specifies higher DC voltages for the pins than the SN65HVD1050 does. Why is the TCAN1042 less robust for transients than the SN65HVD1050? Does TI have an IC that has the DC voltage rating of the TCAN1042H and the transient robustness of the SN65HVD1050?

    Thanks again,
    Toby
  • 0 in reply to Toby Doorn
    Prodigy 120 points
    Hi Max,

    More specifically, we are looking for the load dump specification, test pulses 5a and 5b. For the SN65HVD1050 it is specified that it can meet +/-200V for these pulses, but for the TCAN1042H, no specification is given. Do you have documentation for the TCAN1042H for this spec?

    Thanks and regards,
    Toby
  • 0 in reply to Toby Doorn
    TI__Guru 74252 points

    Toby,

    Max is currently out on vacation, but I am looking into this and will have an answer by the end of the day today CST time.

    Regards,

  • 0 in reply to Toby Doorn
    TI__Guru 74252 points

    Toby,

    As of right now, I am only able to find test results for pulses 1, 2, 3a, and 3b on TCAN1042 as mentioned in the datasheet, and it looks like the device was only tested up to the limit required in the standard. There's no mentioning of attempting a higher value and failing. With older devices, all pulses were tested to failing point or an arbitrarily high voltage, but it was decided to align with OEM certification and not necessary to test up to +/-200V if no one requires it in the approval of transceiver devices.

    From what I understand of these devices and how they were designed, if the SN65HVDA1050 can withstand the transient pulses up to +/-200V, than the TCAN devices should be able to as well, given that there structures can handle higher voltage in general. But with no test data at the moment to prove that, I can't guarantee those results.

    Would it make the customer more comfortable if we tested the TCAN1042 to a higher voltage level?


    Regards,

  • 0 in reply to Eric Hackett
    Prodigy 120 points

    Hi Eric,

    According the datasheet, the SN65HVD1050 was tested for ISO7637 pulses 1, 2, 3a, 3b, 5, 6, and 7 (+/- 200V), whereas the TCAN1042H datasheet does not mention ISO7637 (the EMC test report does). Transient pulses are covered with a reference to IEC61000-4, with an EFT of 4kV being specified. While this is a much higher voltage than used in ISO7637, the load dump pulses of ISO7637 last much longer than the EFTs of IEC61000. The EMC report of the TCAN1042 specifies lower voltages than specified for the SN65HVD1050 for ISO7637 pulses 1, 2a, 3a and 3b, and no data is given for pulses 5, 6 and 7. All this makes the two ICs difficult to compare in terms of robustness.

    To come back to your question: Yes, it would make us more comfortable if test results could be shown that prove that the TCAN1042 can indeed match or exceed the SN65HVD1050 ISO7637 load dump test results. If TI would be willing to produce these results, that would be much appreciated.

    Thanks and regards,

    Toby

  • 0 in reply to Toby Doorn
    TI__Guru 74252 points
    Toby,

    You are correct, the TCAN1042H does not mention ISO7637 because this is an Automotive standard and the TCAN1042H is not an Automotive qualified device. The TCAN1042H-Q1 datsheet does mention, but again, they aren't up to the same levels as SN65HVDA1050, thought the absolute maximum ratings on the TCAN1042 are higher across all pins.

    I understand this does make it difficult to compare the two devices in terms of robustness, and this was an oversight on our part. I will look into the testing platform availability and let you know as soon as possible.

    Just for curiosity, what kind of application is this?

    Regards,
  • 0 in reply to Eric Hackett
    Prodigy 120 points

    Hi Eric,

    I had not made the link between the Q1 suffix and ISO7637, also because the SN65HVD1050 (without Q1) datasheet does mention ISO7637.

    We design and sell autonomous energy systems, using 12V, 24V and 48V batteries. We have had failures of the SN65HVD1050 in the field and are having an internal debate whether additional protections are still required if we switch to the TCAN1042H. If the TCAN1042H turns out to be significantly better, perhaps we can leave the protections out.

    Thanks for you excellent support!

    Regards,

    Toby