Carrier board design auto-power-on


I am designing a custom carrier board for Jeston TX2.

I don’t want to have any power or reset button, and the board should automatically power on when the power connected.

I read the Jetson TX2 OEM Product Design Guide, Jetson TX2 Developer Kit Carrire Board Specification (specially the APPENDIX describing the auto-power-on rework), and the given P2597_C02 schematic.

From all descriptions, I concluded that I should do the following:

1- The ACOK pin (CHARGER_PRSNT#) should be tied to ground.

2- The resistors R383 and R384 , and hence the driving transistors are not required (Q42, Q43, Q44).

3- The gate of Q30 should be connected to ground using a 10K resistor, and the resistor between gata and source of the transistor removed.

4- The MOD_CFG_ID_L signal teid to ground (add wire between Q47 source and drain).

(The above four changes are mentioned in the Carrier Board Specification file.
But I deduced another result from the schematic:)

5- Page 19 and 20 of the P2597_C02_Concept_schematics file can be completely ignored.

Is my conclusion right?

I know this is differ from the power-up sequence and i carefully followed the instructions about that.


The power sequence and auto power on design are included in TX2 series product design guide in DLC. You should follow that to make custom design.

Yes I read that file.
The TX2 series product design guide refers to the P2597 schematic almost in every section. Now I have a question about that file,
And I think the simple “follow the guide” sentence do not solve all potential problems.

Anyway, thanks for your response.

The product design guide has listed necessary requests. For custom design, just need to follow the chapter 4.POWER part. For auto power on function, following below guide will be OK.

4.8.1 Jetson TX2/TX2 4GB Auto-Power-On Details
For Jetson TX2/TX2 4GB, to enable this feature, the CHARGER_PRSNT# pin should be tied to GND. To power the system on without a power button, a specific sequence is required between the time the VDD_IN power is connected and the CHARGER_PRSNT# pin on the module is driven low. The CHARGER_PRSNT# pin connects to the module PMIC and requires a minimum delay of 300ms from the point VDD_IN reaches its minimum level (5.5V) before it can be driven low. Jetson TX2/TX2 4GB includes circuitry on the module to support Auto-Power-On.

Thanks for your kind reply

The 300ms delay between VDD_IN and CHARGER_PRSNT# is provided on Jetson TX2 module itself? Or should be provided on carrier board?
The P2597_C02 schematic suggest that connecting the CHARGER_PRSNT# pin to GND is enough for auto-power-on.

The 300ms depends on custom design.


I don’t understand this.

I will describe my peoblem in another way:

Is connecting the CHARGER_PRSNT# pin to ground enough for auto-power-on of Jetson TX2? (As developer kit guide auto-power-on rework ; and the OEM DG suggest)

Or a 300ms delay is required between the VDD_IN minimum level time and the time at which the CHARGER_PRSNT# is driven low?

Also please note this section, which explicitly says that the CHARGER_PRSNT should be tied to GND:

Sorry for misunderstanding your question. The 300ms is monitored in module by circuit design. Connecting CHARGER_PRSNT# to GND is enough.

No problem.
May be due to my bad understanding or bad English.

Thanks Trumany!

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