• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 33 subscribers
  • Views 573 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

TCAN1044A-Q1: VBat short circuit current and split termination package.

Raviteja Gandi
Prodigy 10 points
Part Number: TCAN1044A-Q1


Dear Team,

I'm using TCAN1044ADRQ1 IC in my project. I have small doubt on the transceiver. 

1. Is the Short-circuit steady-state output current, dominant Normal mode {IOS(SS_DOM)} of 115mA is the maximum limiting current of the (CAN_H, CAN_L) Pin's or the maximum with standing current rating of the Pin's.  

2. What happened TCAN1044A if we exceed 115mA of current rating (Will it work or damage the transceiver). If it works continuously or will go to any fail-safe mode like (Over current protection or thermal shut down). 

3. Could you please suggest me the CAN bus split termination resistors package (Power dissipation) for 60 Ohms. Considering the Vbat (9V~16V) fault condition on the CAN_H, CAN_L pins (CAN bus). Calculation for the same.

Thankyou in advance.

Best Regards,

Raviteja

  • 0
    TI__Mastermind 30620 points

    Hi Raviteja,

    1. It is the maximum short circuit output current in dominant state, which is a protection feature of our device.

    2. Due to short-circuit current limiting it should keep the self-heating to a level. If the heat can't be dissipated then it could cause thermal shutdown but the device won't be damaged.

    3. Please find this chart in datasheet

    Regards,

    Sean

  • 0 in reply to Sean Guo
    Prodigy 10 points

    Hi Sean,

    Thanks for the clarification!

    Since, the point No.3 is regarding the TCAN1044A electrical parameters you have mentioned, and I got really confused.

    So, could you please suggest me a resistor package (Like 0805(125mW), 1206(250mW) along with power dissipation) for split termination (120Ohms: 2x 60Ohms and 4.7nF) of single resistor and also evening considering the Automotive transients on VBat(Jump start and load dump).

    Best Regards,

    Raviteja.

  • 0 in reply to Raviteja Gandi
    TI__Mastermind 30620 points

    Hi Raviteja,

    Sorry that I misunderstood your question. The power rating of the termination resistors will depend on how many faults are being designed for at the same time. According to the datasheet, the maximum short-circuit steady state output current on the bus is 115mA, meaning that in a fault case, it is limited to 115mA.The most conservative approach would be using the worst case where the entire battery voltage is being dropped over the termination resistance. In this case, 1.5 W would be dropped over both resistors, and thus 0.75W in each 60 ohm resistor. For the case where the bus is shorted to battery and the bus is dominant, 0.3 – 0.4W across two 60 ohm resistors would be 0.15 – 0.2W, which would be covered by 1206 resistors, which can withstand 0.25W of power.

    We've also seen customer using terminations resistors in smaller packages such as 0805 125mW or 0604 100mW. (We use 0603 package in our EVM board) It really depends on how many faults you expect to happen in your system. 

    Regards,

    Sean