• State
  • Locked Locked
  • Replies 5 replies
  • Subscribers 34 subscribers
  • Views 177 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TCAN1164-Q1: transient thermal impedance

Yusuke Mukuno
Expert 7395 points
Part Number: TCAN1164-Q1

Hi expert, 

My customer is requesting the data of the transient thermal impedance for TCAN1164.

Do you have any data for the transient thermal impedance?

Generally, the transient thermal impedance is for FET device, power device or something,

But, if you have any data or comment, please let me know.

Thanks,

Mukuno

  • 0
    TI__Genius 15345 points

    Hi Mukuno-san,

    The only data on thermal impedance that we have is the thermal resistance data in the datasheet:

    Is this enough information for your customer?

    Best,

    Chris

  • 0 in reply to Chris Ayoub
    TI__Expert 7395 points

    Hi Chris-san,

    It is not enough.

    They would like to know the transient thermal impedance data.

    Customer have to consider about  transient thermal impedance, because the LDO is integrated in TCAN1164.

    Can you take the data for this device?

    Thanks

    Mukuno

  • 0 in reply to Yusuke Mukuno
    TI__Guru 65792 points

    Mukuno-san,

    Transient thermal impedance is typically depicted as junction-to-case thermal impedance and is in units of C/W. The values in the datasheet are simulated with full IC characteristics and design in mind, including the integrated LDO. Can you elaborate on what exactly the customer wants?

    Regards,

    Eric Hackett 

  • 0 in reply to Eric Hackett
    TI__Expert 7395 points

    Hi Eric-san

    The reason for asking this question is to calculate the amount of time that the MCU driven by the LDO will not malfunction if the current increases during a CAN-H ground fault and leads to thermal shutdown.

    It is assumed that when CAN-H goes into a ground fault condition, the SBC current increases and the temperature rises.
    When a CAN-H ground fault occurs, a large amount of current does not always flow, but it will flow periodically.

    I think it is necessary to have a process to stop the data output from the MCU before thermal shutdown.

    If you know the heat capacity, you know the thermal resistance (described in the data sheet), so you can estimate to some extent.
    If you know the volume, weight, and specific heat, you can get a rough estimate of the heat capacity, so if this is easier than the transient thermal resistance characteristics, there is no problem with this data.

    Thnaks

    Muk

  • 0 in reply to Yusuke Mukuno
    TI__Guru 50115 points

    Hi Muk,

    From the CAN point of view here, the amount of time that the transceiver is driving the fault current is limited by the CAN protocol layer. When a high current fault occurs such as CANH to GND, the CAN bus will no longer be able to properly transmit a dominant state. Because CAN controllers monitor the bus state during transmission, the local node will be able to recognize this fault has occurred and stop driving the transceiver to the dominant state after only a few attempts. In addition to this protection built into the standard, TCAN1164 supports a bus fault detection feature that can notify the MCU when such a fault occurs so that no new transmission attempts are unnecessarily attempted. 

    In either case, the actual driving time of the CAN transmitter will be limited to only a few CAN frames before transmission attempts will cease. The fault dominant time will be dependant on data rate and error counter configuration of the CAN controller, but will most likely be limited to a minimally impactful if at all on the thermally performance of the device. 

    Regards,
    Eric Schott