Amperage Question

[weaversam8]

Hi CD,

Our team is considering using the NVIDIA Jetson TK1 on our robot for vision processing, but it takes 12V 5A. What would be the smartest, easiest, safest, and most legal way to get that kind of power to that board?

[MrForbes]

Read the rules about powering Custom Circuits, and see what you come up with. You might want to check to see how low of voltage the computer will operate, since the main connections on the power distribution board will have varying voltage, depending on other loads on the robot (such as drive motors operating)

[Amar Shah]

Here's some information about the power requirements of the board: http://elinux.org/Jetson/Jetson_TK1_Power

The board itself typically uses 5W, though you could peak at 15W if you were fully maxing out the CPU and GPU capabilities. However, you can draw more power with peripherals - SATA, HDMI, USB3, flash memory can all draw a significant amount of power. I would measure the current the board actually draws for your usage case, and see if you can get away with a lesser power supply. I suspect you would be able to get away with using the 12V 1.5A terminals on the VRM.

[DonRotolo]

but it takes 12V 5A.From where did that specification come?

Regardless: 5 Amperes (if, in fact, that value is accurate) is easy to pull directly from the PDP. Our CIM motors are protected at 40 A.

[weaversam8]

The power adapter for it specifies 12 volts 5 amps MAX. You really think 2A would be enough?

[Amar Shah]

The power adapter for it specifies 12 volts 5 amps MAX. You really think 2A would be enough?

Did you look at the link I posted? That 5A rating on the power adapter is so that the board can power a full assortment of peripherals connected to it. If you aren't powering a lot of peripherals, you will get less current draw.

[weaversam8]

Apologies. I think I missed your post when I posted mine. Our electrical team got it working on one of the 20A sockets tonight.

[dtengineering]

Just recall that the PDP gives 12V nominal voltage... it is basically a direct (breaker protected) connection to the battery.

When your motors draw oodles of amps, particularly near the end of a match, you aren't going to get 12V off of it. <edit> Just checked the specs... it calls for 9.5V to 12V. I have definitely seen our past robots drop below 9.5V (briefly) while in operation. This could cause your board to re-boot in the middle of a match. </edit>

The old IFI Robot controllers carried a backup battery to maintain operation during current spikes (and the subsequent voltage drops).

I'd suggest testing it with a slightly used battery and all of your motors stalled.

You might want to consider a DC-DC voltage convertor if you run into problems.

Jason