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TCAN4550: TCAN4550

Arabella Zhang
Intellectual 2990 points
Part Number: TCAN4550

Tool/software:

Dears,

I have a question about the sleep of TCAN4550.
1. After the customer configured TCAN4550 to enter sleep mode, the voltage of its VCCOUT pin dropped from 5v to 1.1v, but there was still current output. The customer is still testing the source of the current. What is the possible reason?
2. At the same time, I would like to ask, where in the configuration of sleep mode will affect the output of VCCOUT of TCAN4550?

Thanks,

Arabella

  • 0
    TI__Mastermind 33440 points

    Hi Arabella,

    Arabella Zhang said:
    1. After the customer configured TCAN4550 to enter sleep mode, the voltage of its VCCOUT pin dropped from 5v to 1.1v, but there was still current output. The customer is still testing the source of the current. What is the possible reason?

    The internal 5V LDO that supplies the VCCOUT pin is disabled during Sleep Mode, however, there is still decoupling capacitance that needs to discharge.  My observations show the VCCOUT voltage drops to 0V when the device enters sleep mode. 

    How much current is being drawn, and over what period of time after the device has entered Sleep Mode is this voltage and current being measured?  Please provide actual data plots for review if they believe the current and voltage levels are coming from the TCAN4550's VCCOUT pin.

    Arabella Zhang said:
    2. At the same time, I would like to ask, where in the configuration of sleep mode will affect the output of VCCOUT of TCAN4550?

    The VCCOUT LDO is turned OFF in Sleep Mode, and there are no register configuration settings that will affect the output voltage or current levels in Sleep Mode.  In fact, there are no configuration registers that will affect the VCCOUT LDO in ANY way.  It is not configurable.

    Regards,

    Jonathan

  • 0 in reply to Jonathan Nerger
    TI__Intellectual 2990 points

    Thanks for your reply.

    When the CAN bus goes wrong, VCCOUT cannot be output to the outside?

    Many thanks!

  • 0 in reply to Arabella Zhang
    TI__Mastermind 33440 points

    Hi Arabella,

    I'm not sure I understand what you mean by the "CAN bus goes wrong".  Are you referring to some sort of fault condition where the CANH and CANL bus pins experience some sort of open or short condition such as one or both are shorted together, to GND, or to a supply voltage?

    I also don't know what you mean by "outside."  The TCAN4550's Internal 5V LDO has a total current capacity of 125mA, and it can provide up to 70mA of current to a local circuit connected to VCCOUT pin of the device such as an MCU, or some digital logic circuits.  The VCCOUT should not be used to supply power to any other boards through some sort of cable connection.

    However when there is a CAN bus fault condition such as a short to GND, there can be a high current draw from this 5V LDO and it could impact the amount of current and voltage levels on the circuitry connected to the VCCOUT pin.

    Regards,

    Jonathan