Input voltage fluctuation will cause the system to power down

My TX1 board input power is 16V . The system work is fine. When the power suddenly drop to 14V the system will power down. Somebody have any hint to fix this problem?. I tried the EVM board of Nvidia . It’s has same problem.

Hi SHJ1999,

How fast the drop is? Why does this drop happen?

When the main input power switch to backup battery . The input power has this drop. The drop and jump time is about 1ms.

What’s this backup battery? How and why does this (main input power switch to backup battery) happen? Un-plug main power supply?

Sometime we need unplug main power and change it. We don’t like shutdown the system. The backup battery will power the system when the main power unplugged.

Then where do you connect backup battery to? VDD_IN?

We check the data sheet of TX1. The input power voltage is 6V—19V . I think there is a DC-DC converter in TX1 module and this module input range is 6–19V. This is the reason we connect the backup battery to VDD_IN. Can you give me some request about the VDD_IN?

Yes, there is a DC/DC converter in module, its input range is 6–19V. But you need to take care of the transient input drop when switch the power supply.

Just estimate the possible cause as not see your detail circuit design.

Are you using 16V power to charge backup battery before unplug it? If so, it is strange that the voltage will drop to 14V suddenly, maybe the backup battery is not charged to 16V fully or its output capability is limited?

As you can see, there are some capacitors on VDD_IN, and they are charged to 16V certainly before unplug power supply. If your backup battery is connected to VDD_IN and is not charged to 16V, when unplug power supply, the capacitors will have to charge the backup battery and supply the system at the same time. That will cause system transient out of power as capacitors’ output capability is not enough.

Thanks for your support. I did a testing with Nvida’s EVM board. My power supply is Agilent E3634A. It’s an adjust DC power supply. The input voltage is 15V . The system work is fine. I quickly adjust the input power to 14V. The system as same as mine. It shutdown . The capacitors on VDD_IN is 56uF in Nvida’s SCH . I used the same value . I changed the capacitor to 100uF. The result is same.

Does battery power the Jetson directly, with the battery charge source disconnecting? Or does battery indirectly reach the Jetson through a regulator?

If battery directly powers Jetson without intervening regulator circuitry I would not expect a power drop to cause shutdown; if Jetson is indirectly battery powered I would expect a very short spike to cause shutdown since the regulator takes a moment to adjust for power source (especially a switching design regulator…a linear regulator would be less subject to this spike; also current limiting circuitry in a regulator may get in the way during a spike).

Hi, Linuxdev
I used Agilent E3634A DC power supply directly power the TX1 EVM board . The problem is same when I adjust the power supply voltage from 15V to 14V quickly by hand. I monitored the input power to VDD_IN with oscilloscope and didn’t see any spike.

Spikes of very short duration could be an issue. I’d suggest powering the Jetson directly from battery, and using the external supply to in turn charge battery. Direct connection of supply to Jetson means current limiting on the power supply might get in the way, especially if current limiting is foldback instead of linear. Measuring a spike would be very difficult without a quality recording oscilloscope…and knowing if more current would be available without current limiting would be even more difficult.

Hi SHJ1999,

Seems you tested power supply with DC source directly, in this situation, tuning output voltage so far so quickly could cause big drop ripple on the input of DC/DC, it might cause a big ripple on the output and so might cause system power down.

I am also facing similar issue wherein as soon as the system connected to the charger , the processor gets rebooted. In our case we are supplying 12V to Tegara TX1 which is being generate by a DC-DC which is converting 48V of battery to 12V.

In our system battery is connected directly to the charger output and also to the input of the DC-DC.

What could be the reason for this reboot.
We have observed some noise on the 12V supply but it is of high frequency of 10KHZ