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  1. #1
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    ATA6561 getting shorted frequently

    Hello and greeting everyone and Happy new year.

    I have designed a circuit of CAN communication using a MCP2518FD CAN controller and ATA6561 CAN transreciever. I am using a buck converter to give 3.3V dc to the circuit and, giving a supply of 12V input the system. My transreciever is getting short-circuited most of the time. I am not able to figure out what is happening to the system.

    Click image for larger version. 

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    This is my Schematic for CAN communication and
    Click image for larger version. 

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    This is my power supply.

    Please suggest me any error which could be the reason for this issue. Please ask me for any further questions which I have not provided here.

    Thank you
    --Md Shahrukh

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    Re: ATA6561 getting shorted frequently

    What do you mean your “transreceiver is getting short-circuited most of the time”? That’s not very descriptive. Is there zero resistance across the power supply pins? Does the device get very hot and fail?


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  3. #3
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    Re: ATA6561 getting shorted frequently

    Hi,

    Semiconductors fail because of
    * overvoltage, even in the microseconds
    * overcurrent
    * overheat

    Overvoltage may be caused by ESD. Maybe by supply voltage peaks caused by bad PCB layout in the switch mode power supply section.

    --> show us your PCB layout
    Tell us exactly where and how you detected the short circuit.
    Tell us about the connected devices, photos may be helpful

    Klaus
    Please donīt contact me via PM, because there is no time to respond to them. No friend requests. Thank you.


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  4. #4
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    Re: ATA6561 getting shorted frequently

    Click image for larger version. 

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    This is my PCB layout. And The IC was getting hot, from that, and while checking voltage across the multimeter it doesn't show any voltage and after removing the supply I found the 3.3V pin and ground is getting shorted which I have tested with a continuity test using a multimeter. I got to know that the ATA6561 IC was short-circuited. Because when I removed the voltage reference pin of ATA6561 from the IC PAD (footprint) the 3.3V and Ground pin was normal and was not showing continuity.

    I have not provided TVS diode at the CAN-H and CAN-L pins, could be this is the reason?

    There are many devices connected to my PCB. Like, TMS320f28069 microcontroller, ENC28J60 Ethernet controller, DS3231 rtc, AT24C32 EEPROM, MAX4781 analog multiplexer, DAC7678 for D/A conversion, SP3232 uart-to-rs232 convertor, MCP23S17 GPIO expander. These are connected in 3.3V supply along with those CAN ICs.

    I want to correct a few things, here ATA6561 operating voltage is 5V dc and 3.3V is connected to voltage reference pin of the IC. And these two pins are short-circuited.

    Thank you.
    --Md Shahrukh



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    Re: ATA6561 getting shorted frequently

    Hi,

    I see no GND plane, (so internal ESD protection can't work satisfactory)
    I see no external ESD protection. No Connector shield connection..

    This is no PCB layout. It's just connecting some signals with tiny traces.
    I assume this is the same with microcontroller and SMPS....

    --> no wonder it fails. You need to learn how to do a proper PCB layout. There are many discussions here, many tutorials in the internet.

    Klaus
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  6. #6
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    Re: ATA6561 getting shorted frequently

    I have provided the ground Plane, Eagle pcb tool appeared it that way.
    Here is the complete layout.
    Click image for larger version. 

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    --Md Shahrukh



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    Re: ATA6561 getting shorted frequently

    Hi,

    It is "copper pour" but no GND plane.

    And the picture is of poor quality.
    Either EXPORT a 600dpi PNG file, or make a screenshot as PNG to get good quality, and small filesize pictures.

    Klaus
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    Re: ATA6561 getting shorted frequently

    Voltage sequencing.

    Have your read the data sheet and verified the timing relationship between voltages at power up?

    It might be a non-issue, but please check it out.



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