TPS65381-Q1 State transition by IGN and IGN_PWR, WR_CAN_STBY and IGN(No.122)

Q1:

Please advise if TPS65381 stays current state or transition to another state in following case.

Wake-up by IGN signal and following change occur at the same time internally. (IGN low-to-high)

1. -IGN changes High to Low.
2. -IGN_PWRL changes Low to High.

[A] Assuming above two events (#1 and #2) occur at the same time.

Device will not change the state (it will remain in the same state).

It takes up to 20 ms to detect IGN pin state change, while it takes 4 to 5 system clock cycles (after SPI command) to set the IGN_PWRL (the ignition power latch). By the time valid IGN low state is detected, the IGN power latch bit is already set that will keep the device in powered-up state while IGN pin is low.

Q2:

Please advise if TPS65381 stays current state or transition to another state in following case..

Wake-up by CANWU signal and following change occur at the same time internally.

  -IGN changes Low to High.

  -Received WR_CAN_STBY command.

[A] It takes 4 to 5 system clock cycles to ‘process’ WR_CAN_STBY command and start device shut-down procedure (powering down). AT the same time, wakeup circuitry keeps de-glitching IGN pin state. It takes up to 20 ms to detect valid IGN high state that will cause device to start-up again after all VDDX rails are fully discharged.

Once power-down sequence is initiated, it has to complete till full device power-down before any new wake-up event can restart device (in other words, no wake-up event can interrupt ongoing shut-down sequence). (shut-down means transition to STANDBY state)

Hello Mahmoud-san,

Thank you very much for your answer.

 I can understand your answer but customer’s question is state change when internal two signal transition occurs at completely same time.

I write chart in case of internal signal transition occurs at same time referring your answer as below.

Please answer if state transition will occur or not in case of internal signal(IGN and IGN_PWRL, IGN and CANWU_L) transitions at completely same time for Q1 and Q2.

Thanks and Best regards.

Hello Mahmoud-san,

Please answer for my above additional question.

Best Regards.

I believe the device will not change state in these situation but I will double check with the designer. It is very difficult to check these situations on bench

Hello Mahmoud-san,

Thank you for your reply.

I agree that it is difficult(impossible) to check these situation on bench, so please check with the designer.

I am looking forward to your reply.

Thanks and Best Regards.

I checked with the designer and the answer is the device will not change state