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Original question:

TCAN2450-Q1: need for a separate external LDO?

TCAN2450-Q1: cyclic sense wake

JOONGGEON LEE
Prodigy 70 points
Other Parts Discussed in Thread: TCAN2450-Q1

1. I would like to ask you how to wake-up in sleep mode when using TCAN2450-Q1.
Please explain how to do cyclic sense wake design other than wake-up using mechanical switch.
ex) some sort of relay, FET, other mechanism

2. When configuring cyclic sense wake for HSS4 and WAKE1, it is said that you need to connect to the wake signal source so that you can detect the wake, so please explain how to connect in the attached Logic.   

    UWB(R5)_Slave(Schematic)_VER0.0(20231024).pdf    

  • 0
    TI__Mastermind 33030 points

    Hi JOONGGEON,

    JOONGGEON LEE said:
    1. I would like to ask you how to wake-up in sleep mode when using TCAN2450-Q1.
    Please explain how to do cyclic sense wake design other than wake-up using mechanical switch.
    ex) some sort of relay, FET, other mechanism

    You could use a transistor or a FET that could be enabled to sink the current from the HSS pin and pull the WAKE pin "Low" during Cyclic Sensing Wake.  When the transistor or FET is not active, the WAKE pin will see a "High" voltage from the HSS pin.

    JOONGGEON LEE said:
    2. When configuring cyclic sense wake for HSS4 and WAKE1, it is said that you need to connect to the wake signal source so that you can detect the wake, so please explain how to connect in the attached Logic.   

    “Cyclic Sensing” is simply periodically sourcing some voltage/current through the High Side Switch to the WAKE pin and external circuit components so that the device can determine if the WAKE input is above or below the configured threshold.  This still requires some sort of external switch or load that will cause the WAKE pin to be either high or low when the HSS voltage is active.  This allows the overall current consumption to be reduced in Sleep Mode because there is not a “static” voltage source that will be constantly sourcing current through the pullup resistor and switch circuit.  The current will only flow for small moments of time when the HSS is in the active portion of the sensing cycle.  The WAKE and HSS4 pins will be synchronized so that they can “sense” the switch state to determine if there has been a change and the device needs to “wake up”.

    In your provided schematic you will still need some sort of mechanical switch or transistor circuit that will pull the WAKE pin voltage “Low” when the HSS4 pin is sourcing a “High” voltage.  There is no difference between the static and cyclic sensing wake applications in this regard. 

    Regards,

    Jonathan

  • 0 in reply to Jonathan Nerger
    Prodigy 70 points

    Thank you for replying

    As you said, I connected Wake Pin using Transistor.
    Please check the attached file again.

    And even if VCC2 is off in Sleep mode, is it correct that CAN transceiver is possible through programming?
    If possible, can I set the active portion of the sensing cycle for HSS4 in Sleep mode through CAN Transceiver?

    UWB(R5)_Slave(Schematic)_VER0.0(20231102).pdf

  • 0 in reply to JOONGGEON LEE
    TI__Mastermind 33030 points

    Hello Joonggeon,

    I have reviewed your schematic again and I don't see what the actual wake up signal source is.  In the basic diagrams, the transistor replaces the mechanical switch.  This is the same for both the Static and Cyclic Sense Wake applications.  The difference between the Static and Cyclic Sense Wake applications is simply that HSS4 replaces the VBAT as the voltage/current source.  When HSS4 is active, the control signal on the transistor will either cause the current to flow through the transistor resulting in a Low voltage sensed on the WAKE pin, otherwise WAKE will see a High voltage.

    JOONGGEON LEE said:
    And even if VCC2 is off in Sleep mode, is it correct that CAN transceiver is possible through programming?

    Yes, the Sleep to Restart Timing diagram shows that VCAN can be low when a WUP is received.  If VCC2 supplies VCAN and is turned off in Sleep Mode, it will need to be turned back on by the MCU as part of the re-initialization sequence before CAN communication will be possible.

    JOONGGEON LEE said:
    If possible, can I set the active portion of the sensing cycle for HSS4 in Sleep mode through CAN Transceiver?

    The sensing cycle can only be configured through SPI.  But you could have a dedicated CAN message that could be received by the MCU that contains the configuration information.  So yes you can, but this needs to be handled in the MCU firmware.

    Regards,

    Jonathan

  • 0 in reply to Jonathan Nerger
    Prodigy 70 points

    If I wake up using the wake-up pattern (WUP), UWB(R5)_slave(figure)_VER0.0(20231024), which I shared. Should I float the HSS4 pin in the pdf file and connect the WAKE1/ID1 pin to GND?

  • 0 in reply to JOONGGEON LEE
    TI__Mastermind 33030 points

    There are multiple options for Wake Up signals including both the wake-up pattern (WUP) and Cyclic Sense Wake using HSS4 and WAKE1/ID1 pin combination.  The other WAKE pins can also be configured as additional options. 

    You are not required to use any specific method for wake-up.  If you do not want to use the Cyclic Sense Wake method, then you can float the HSS4 and ground WAKE1/ID1 pin.

    Regards,

    Jonathan