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TCAN1167-Q1: Pin configuration and design suggestions

Genius 14659 points
Part Number: TCAN1167-Q1
Other Parts Discussed in Thread: TPS3704-Q1,

Hi Experts,

We have this report from a known customer, for your assistance:

I have attached the simple block diagram of the interfaces. We are merging both reset inputs from supervision circuit and can sbc, further it is connected to microcontroller reset.



If we get reset low from supervision circuit, nrst(bidirectional) of can sbc also get low because of its interconnection. If we connect in such a way, due to low reset complete can sbc will move to sleep mode(TXD and RXD will be maintained low). Data transaction through can bus got stopped. Which will disable the enable signal to voltage regulator block. Which leads the complete unit to get disabled.

To avoid that, what kind of circuits we can add in between both reset signals?
Based on it, we can stop signal input to nrst pin which disables the can bus transaction. Which can used for retry options

For our case, we planned to use nrst signal from can sbc as an output alone. Bidirectional operation not required.

Give your suggestions by adding which block we can avoid the reverse flow to can sbc.

Regards,
Archie A.

  • Archie,

    You could use a diode with pull-up resistors on either side to prevent a low signal from TPS3704-Q1 from appearing on the TCAN1167-Q1. When the cathode is facing the TCAN1167-Q1, this would still allow it to pull low and pass a low output, but it would not see low inputs from the supervisor.

    Best,

    Danny

  • Hello Danny,

    Thanks for your suggestions.

    If we connect cathode side of diode to TCAN1167-Q1, then it will work as in input pin alone. Whereas we need to use as output (high). For that we planned to connect both inputs from supervision circuit and can sbc as an input to AND gate, output is connected to reset pin of microcontroller.

    If we connect in such way, our requirements will get fulfilled right. If any incompatibility in logic or any other suggestions let me know.

    Regards,
    Archie A.

  • Archie,

    On a diode, current flows from the anode to the cathode. If connected such that the cathode is facing the TCAN1167-Q1, the low signal output from TCAN1167-Q1 would be passed to your MCU, but the low signal from the TPS3704-Q1 would not be passed to the TCAN1167-Q1.

    You could also implement using an AND gate as you mentioned, this would just require different routing/powering considerations.

    Best,

    Danny