We are working on a custom carrier board and I wanted to validate some of the assumptions I made regarding the power down structure of the module. Based off of the design guide:
- For power up, all carrier board power is enabled AFTER the SYS_RESET* signal is de-asserted.
- During a controlled shut down, POWER_EN signal on the carrier board and the local carrier board power enable is de-asserted when the SHUTDOWN_REQ* signal is asserted by the module (timing being met as described in the design guide).
I am mainly concerned about the sudden power loss situation. My questions are:
Can the carrier board assert the SHUTDOWN_REQ* signal (ie it would monitor the main power input to the carrier board and signal when the module needs to shutdown in the event of a power loss)? Or is this only an output from the module?
If the SHUTDOWN_REQ* can not be driven by the carrier board, when can we expect this signal to be asserted in the event of a sudden power loss? Does the SHUTDOWN_REQ* signal get asserted by the module when it sees the main VDD_IN starting to drop? If this is the case, what level does the module assert the SHUTDOWN_REQ*?
please also check below topics as see-also
Thanks for the references.
Additional question on how the dev kit handles the force_off*:
Understood that this signal is either controlled by the Shutdown_req* or removing the power from the DC power jack. Does the controller then just pull the POWER_EN low through the U22 buffer? (ie. the way that the dev kit tells the xavier to it needs to turn off is by simply removing the POWER_EN?)
it’s SHUTDOWN_REQ* must always be serviced by the carrier board to toggle POWER_EN from high to low.
Okay, but I am still a little confused.
How does the SHUTDOWN_REQ* get asserted by the NX module in the event of a sudden power loss in order for the carrier board to respond? Does the NX module monitor and trigger this signal when the VIN drops to a certain low point?
On the dev kit, when the DC power jack is removed, does the FORCE_OFF* signal make the power microcontroller on board to somehow tell the xavier it needs to shut down, then the xavier commands a shut down (which then asserts SHUTDOWN_REQ* for the carrier board to respond to and remove POWER_EN)?
Thanks again for the help!
you may also access Jetson Xavier NX Product Design Guide,
please read chapter-5.1, [Power Supply and Sequencing] for details.
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