WARNING - SYSTEM Voltage Droop detected, please refer to the Jetson Power management application note

Autonomous Machines Jetson & Embedded Systems Jetson TX1
1

On my custom TX1 carrier board when I switch over to battery backup power
(I remove main external DC power and switch over to onboard batteries)
I see repeated prints of this message in sys log:

WARNING - SYSTEM Voltage Droop detected, please refer to the Jetson Power management application note

Why would this repeatedly be showing? I would think it should only show up once when the main power
supply goes down and we switch over to battery power.

Also, where can I find the document: “Jetson Power management application note”?
I have looked for it in the Embedded Download Center and cannot find it.

2

geoffreywall,
The message resides at device tree and is used inside the kernel,
kernel/drivers/edp/sysedp_reactive_capping.c

tegra210-jetson-cv-base-p2597-2180-a00.dts

The comment should be referring to generic power related docs and there are,

http://developer.download.nvidia.com/assets/embedded/secure/jetson/TX1/docs/DA-08298-001_v01.pdf?autho=1487368585_6fb477b9da4a8de2e35caa699881a696&file=DA-08298-001_v01.pdf

http://developer.download.nvidia.com/assets/embedded/secure/jetson/TX1/docs/TDG-08214-001_v01.pdf?autho=1487368618_dffd45466d2b9a1227ce6dc2ac68ad9e&file=TDG-08214-001_v01.pdf

If you have specific question about power, feel free to submit to Forum. Thanks.

3

Chijen,

thanks for the links to the docs. I believe there is a “specific question” embedded in my post and that is:

[b]On my custom TX1 carrier board when I switch over to battery backup power
(I remove main external DC power and switch over to onboard batteries)
I see repeated prints of this message in sys log:

WARNING - SYSTEM Voltage Droop detected, please refer to the Jetson Power management application note

Why would this repeatedly be showing? I would think it should only show up once when the main power
supply goes down and we switch over to battery power.[/b]

Regards.

4

Hi geo,

What’s the DC power voltage and the battery voltage? How do you do the switch, is it a continuous action or remove DC power first and then turn on the battery output?

As you can see in Figure 7 of OEM DG, if VDD_IN droop 20%, it will trigger VIN_PWR_BAD# to go low and start a power down sequence, can you please probe the VDD_IN and VIN_PWR_BAD# during the switch process to see if they are normal or not?

5

DC Power voltage: 7.5V
Battery voltage: ~6.6V

The switch should be continuous as both the battery and the main switching power supply are connected together
to the load (the TX1) through a Schottky diode. The diode prevents current from flowing back into the battery
when main power (7.5V) is present.

Also, when we switch over to battery backup, we are not seeing the shutdown sequence happening (the TX1 is not shutting down). But what we do see is repeated printk’s to the syslog:

WARNING - SYSTEM Voltage Droop detected, please refer to the Jetson Power management application note

6

What’s your module P/N (699-82180-1000-xxx) ? Did you probe the value of VDD_IN? The VDD_IN value could be too close to the threshold since it is through a diode from 6.6V, that will trigger repeated voltage droop warning.