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TPS65381-Q1 How to go RESET mode by external IGN signal at using IGN_PWRL bit

Other Parts Discussed in Thread: TPS65381-Q1

Hi

My customer is using TPS65381-Q1.
He would like to know how to go RESET mode by external IGN signal at using IGN_PWRL bit.
He uses only Wake-Up by IGN pin.
Could you ansewr the following questions, please?

1.I think TPS65381-Q1 goes RESET mode by a re-cranking on IGN pin at POST_RUN_RST="1".
 But, TPS65381-Q1's mode doesn't change in case of "external IGN signal is high all along".
 Is this correct?

2.If he doesn't set POST_RUN_RST to "1"(POST_RUN_RST is "0"), TPS65381-Q1 doesn't go RESET mode by a re-cranking on IGN pin.
 In other words, In case of POST_RUN_RST="0", TPS64381-Q1 can not go reset mode by external IGN signal at using IGN_PWRL bit
 Is this correct?

Best regards
Shimizu

  • Hi Shimizu-san,

    General IGN_PWRL is a way to provide end of production line programming to the device or use it under MCU controlled scenarios in specific systems.

    A1: If IGN_PWRL has been set, but the IGN pin stays high the device will remain in the powered stated and not go through a reset due to IGN (other system reset sources may still cause a RESET, but not from IGN). This is the same even if you don't use IGN_PWRL, the device will stay "powered" as long as the IGN is high and there is no other system caused reason for RESET or state change. As shown in Figure 5-2, when the IGN_PWRL is set, the device will ignore further state changes (re-cranking, re-starting) on the IGN pin. The IGN_PWRL bit can only be set and cleared in Diagnostic state. If POST_RUN_RST is also set to 1 then the behavior changes slightly. The device will remain in the powered state until then next high going (re-crank) on IGN. At that point the device will go through the RESET state and then into diagnostic state again so that the IGN_PWRL bit could be cleared and the device can be returned to the standard method of using IGN to wake up the device: in normal operation when IGN pin is used to wake up, the device power up state will follow the IGN (Figure 5-1 of the datasheet).

    A2: If the POST_RUN_RST is set to 0, then yes the device will ignore the IGN pin after the first "cranking" or first HIGH on the pin. To clear the bit or RESET the device an alternative method would have to be used, such as CANWU event clears IGN_PWRL

    Best Regards,
    Scott