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TPS65381-Q1: Power management forum

Dilip Namdeo Mohol
Intellectual 1965 points
Part Number: TPS65381-Q1

Hi, Team,

I want to initiate the power down sequence in this PMIC. So I kept the settings in registers as follows:

NO_SAFE_TO = 0

PWD_THR[3:0] = 1

SAFE_LOCK_THR[3:0] = 0

 

I am using watchdog in trigger mode. When I stop giving the pulses to PMIC WD, DEV_ERR_CNT[3:0] increments to 1.

What I expected after this,  ??   Is PMIC to start in standby mode. But PMIC goes to reset mode and board restarts even without ignition signal.

 

When I shutdown the board, I want it to start only when wakeup signal comes e.g ignition. But intended operation is not getting fulfilled.

Let me know your inpust to solve this issue .

Regards

Dilip

  • 0
    TI__Intellectual 1965 points

    Hi ,

    Waiting for solution on my request 

  • 0
    TI__Expert 4950 points

    Hi Dilip,

    Sorry for taking so long to get to answering you. This really shouldn't be happening. Is there any voltage at all on the IGN or CANWU pin? Whenever I try to replicate the issue the device goes into standby mode whether or not a latch is set so long as there is no voltage on either the canwu or ign pin. Could you connect a multimeter up and tell me the voltages at each of the wake up pins. Since IGN is next to VBATP I'm thinking there may be a short between the pins.

    I'm also curious, why aren't you using the canwu or ign latch to power down? It likely wouldn't help here but it is an option. 

    Best,

    Michael Hernandez

  • 0 in reply to Michael Hernandez
    TI__Intellectual 1965 points

    Mike,

    Voltage on IGN Pin:

    Latch is used by system to wake-up. But to shutdown we remove latch and then insert WD error to enter PMIC standby mode. I have checked this on multiple boards and on eval-board given by TI; there is no problem with HW.

     

    Canwu or ign latch to power down:

    For shutdown, do we have to remove latch first? If that’s the case; it is contradicting the fact that we can’t access the registers in active mode.

    If you are suggesting that we control IGN pin directly; then we are losing control over shutdown. We don’t want abrupt shutdown.

     

    Can you send  the register settings that you are doing for standby mode?

    Dilip

  • 0 in reply to Dilip Namdeo Mohol
    TI__Expert 4950 points

    Hi Dilip,

    If you have voltage on the ign pin I suspect that the device is immediately rebooting after shutting off. Try keeping the latch on but taking the voltage off the IGN pin then triggering your shutdown sequence. 

    For the latched shutdown I found that I was able to shutdown from the safe state with the canwu latch by writing 7C to the WR_CAN_STBY register then writing 0 to the same register. You can try that as well, just make sure there is no voltage on the wake up pins. As this is an automotive part the ign pin was expected to be controlled by a mechanical switch (a key). It may be better if you use the canwu pin.

    Hope this helps.

    Best,

    Michael Hernandez