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TPS65950 low power mode couldn't be achieved

Mukesh Bharath Ramalingam
Prodigy 50 points

Hi All,

We are working with TI-DM3725 and TPS69590 and facing issue in sending the device to low power mode and resuming from it.

With the tps69590, low power mode couldn't be achieved properly by clearing the FUNC_CTRL[6].SUSPENDM bit.

When clearing this SUSPENDM bit, ports are getting disabled (i.e., device disabled from device manager) and can see power drop of 40mA in power supply.
but could not resume exiting the low power mode.

When re-plugged the device, device is appearing as "Unknown device recognized".

We have configured the tps unit as per the tech reference manual, didn't find anything specially to be configured for low power mode. if there is anything needs to be taken care, please let me know.

Also I didn't find any relevant errata workaround for this issue. 

Have anyone faced this problem before and if yes, could you please suggest us the
workaround for it.

  • 0
    TI__Genius 10885 points
    Hi Mukesh,

    I'm not sure I understand, how are you attempting to bring the PMIC out of the low power mode?
  • 0 in reply to Richard Solarski
    Prodigy 50 points
    Hi Richard, For getting out of low power mode, I have tried some ways which i have listed below (but, none helped me in achieving that)
    1. Enable the PHY clock by setting the reg PHY_CLK_CTRL[0] REQ_PHY_DPLL_CLK bit to 1 (with this I also set bits CLK32K_EN & CLOCKGATING_EN of same register to 1).
    2. Step 1 with clearing PHYPWD bit of reg PHY_PWR_CTRL (0 - Normal State; 1 - Power down)
    3. Set the SUSPENDM bit of FUNC_CTRL reg followed by Step 1 & 2. (since 0 - Low power mode)

    One thing i have observed constantly through out this process is when I clear SUSPENDM bit of FUNC_CTRL reg and post to that when i read that register, I can still see the bit didn't get clear but the USB ports got disabled and power drop of 40 mA has been happend.
    Is this behavior normal? because I've read in tech reference manual that this SUSPENDM bit will be set by PHY when it exits low power mode.

    please advise.

    Thanks,
    Mukesh
  • 0 in reply to Mukesh Bharath Ramalingam
    TI__Genius 10885 points
    Hi Mukesh,

    I'm not too familiar with the SUSPENDM feature of this device, so I can only go off of the information available in the TRM. I know that this feature will disable register access for the PHY, so what is the host in this scenario and which interface is being used to communicate with the device?