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[C5535] RTC-only mode

Kaka
Guru 24520 points

Hi Community member,

Please let me confirm the following question.

[Question.1]

According to TRM, the power domain should be powered down during RTC-only mode except for LDOI, DVDDRTC and CVDDRTC .
Is there any problem that the system keeps supplying the power for DVDDIO, USB_VDDOSC, USB_VDDA3P3, USB_VDDPLL during RTC only mode?

[Question.2]

Does it need to input the "Pulse" duration over 30.5us in order to wake-up from RTC-only mode? If  keep inputting the "High" signal, does DSP not wake up from RTC-only mode?

If you have any questions, please let me know.

Best regards.

Kaka 

  • 0
    TI__Mastermind 23785 points
    Kaka-san,
    A1: The defination of RTC-Only mode requires LDOI, DVDDRTC and CVDDRTC to be powered. Rest of the power domians CAN BE powered off to achieve the lowest power saving. It is NOT a requirement to power off DVDDIO, USB_VDDOSC, USB_VDDA3P3, USB_VDDPLL during RTC only mode. Just when these power domains are not off, the device is not really in RTC-Only mode. It is in a stage somewhat in between RTC-Only and IDLE 3 configuration. You can refer to the "Power Configuration" table for details.
    A2: Yes. A high pulse for a minimum of one RTC clock period (30.5 μs) to the WAKEUP pin is required to wake up the device from the RTC only mode. No. The pulse has to be low-high-low.
    Regards.
  • 0 in reply to Steve Tsang
    Guru 24520 points
    Hi Steve,

    Thank you for your comments.
    Please let me confirm the following question just in case.
    1. The power domains (DVDDIO, USB_VDDOSC, USB_VDDA3P3) CAN be powered off during RTC-only mode. Thus, there is not any problem for behavior of C5535 even though those domains are powered on during this mode. If those domains are powered on during this mode, the power consumption will be higher than the recommended RTC only mode.
    Is my understanding correct?

    2. If keep to inputted "High" single (not pulse) , is there any problem for the C5535 operation?
    My customer would like to use the wake-up pin as below.
    1. Connect the Power switch to Wake-up pin.
    2. If power on their system, the power switch will be "High".
    3. Wake up the C5535 by this signal but the signal is not pulse.
    Thus I would like to know the behavior when input this signal.

    Best regards.
    Kaka
  • 0 in reply to Kaka
    TI__Mastermind 23785 points

    Kaka-san,

    1. Yes.

    2. In order to wake up device, a "low-high-low" pulse is required. A  MUST. If keeps "High", no pulse, it can not wake up device.

    2.1 and 2.2 are steps. No question. 2.3 question: If customer wants to wake up device here with the "no pulse" signal, Won't work.

    Regards.