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CCS/TPS65381A-Q1: Standby state of TPS65381

yu chen62
Prodigy 140 points
Part Number: TPS65381A-Q1

Tool/software: Code Composer Studio

Dear E2E:

From the datasheet of Tps65381A, I know that there are two ways to clear the IGN_PWRL bit.(put the device into standby state from active state)

1.    A re-cranking on IGN pin

2.    A detected CANWU wake-up event(send the WR_CAN_STBY SPI command)

In our system, the re-cranking on IGN pin cannot meet our requirements.And there is no CAN WakeUp Pin connect to the CANWU pin of the TPS65381.

Question:

Is there any other ways that I can clear the IGN_PWRL bit through the software?

  • 0
    TI__Expert 8810 points
    Yu,
    As you have stated, the TPS65381A-Q1 device has two wake-up pins: IGN and CANWU.

    Below explains how to clear the IGN_PWRL bit through a SPI command:

    The IGN wake-up pin is level-sensitive and is deglitched with the IGN_deg deglitch (filter) time. The TPS65381A-Q1 device provides a power-latch function (POST_RUN) for this IGN pin, allowing the MCU to decide when to power down the TPS65381A-Q1 device through SPI command. For this, the MCU must set the IGN power-latch bit 4 (IGN_PWRL) in the SPI SAFETY_FUNC_CFG register, and read the unlatched status of the deglitched (filtered) IGN pin on the SPI register, DEV_STAT, bit 0 (IGN). To enter the STANDBY state, the MCU must clear the IGN_PWRL bit. For this, the TPS65381A-Q1 device must be in the DIAGNOSTIC state because this SPI register is only writable in the DIAGNOSTIC state. The IGN_PWRL bit is also cleared after a detected CANWU wake-up event. Furthermore, the TPS65381A-Q1 device provides an optional transition to the RESET state after a detected IGN wake-up during POST_RUN (see Figure 5-2).

    Let me know if you need more information.
  • 0 in reply to Gordon Varney
    Prodigy 140 points
    Hi Gordon,
    Thank you for your reply!

    From your reply , I also have two problems as following:
    1. If there is no pin connected to the CANWU pin of TPS65381(the CANWU_L，DEV_STAT, bit 0,is 0) , can I send the WR_CAN_STBY SPI command to clear the IGN_PWRL?(In my test, I failed to clear the IGN_PWRL in the above method.)
    2. If the above method can't pass, is there any other method I can try to clear the IGN_PWRL?(In addition to a re-cranking on IGN pin )

    Hope that helps,
    Regards
    Yu
  • 0 in reply to yu chen62
    TI__Mastermind 20580 points

    Hi Chen,

    There are two wake up pins on the device IGN and CANWU.  IGN is normally used with the ignition line of the vehicle and is normally not latched, meaning if IGN is high the TPS65381A-Q1 is in an operational state and if IGN is low it is in STANDBY.   CANWU is a latched wake up signal, normally from a 14 pin CAN transceivers.. The IGN_PWRL is normally used during end of the production line programming of the MCU in the system.

    Sending WR_CAN_STBY command while IGN or CANWU is still high will do nothing since the wake up request from the pin being high has higher priority.  Sending WR_CAN_STBY will not clear an IGN_PWRL.   A CANWU wake-up event is not sending WR_CAN_STBY, rather it is a low to high transition on CANWU pin.  

    If you need a latched wake up pin, it may be better to use CANWU and externally protect against reverse battery.  Then when the level on CANWU is low you just send WR_CAN_STBY command to go to STANDBY state.

    Best Regards,

    Scott