Hi, I have some info to add re using boost-buck modules to power a Nano via the barrel jack.
In a way answering my own question at Issue with powering Jetson Nano from Boost-Buck converter
and also providing evidence for “system throttled due to overcurrent” messages
As @linuxdev points out “However, unless the regulation is sufficiently tight, you might find the unit shuts down when there is a very short spike in needed current…some cheap regulators can’t keep up with short power spikes”
I finally got access to a scope and could see a couple of issues with all power supplies.
a) what happens at power-on can affect the Nano’s ability to boot at all.
b) the Nano seems to cause a lot of spikes in any unit’s abilty to keep up - this can be seen as large peak-to-peak values. When the Nano is off these go away
In the end I measured powering it directly from the Plug pack and using 4 different boost-buck or just buck modules
I have a switch on my device so there is a consideration to make
- should the switch be AFTER the power module - which means the power module can stabilise before being sent to work
- should the switch be BEFORE the power module which means the nano can benefit from any ‘soft start’ features incorporated
The measurements were V out of the module, at the input plug to the Nano then the internal measurements (which must be what is used for the ‘system throttled’ state)
The attached picture shows the modules. From Left to right they are
- DC-DC 9V/12V to 5V 4A Mini Buck Module Converter Step Down Module ID: 1343488 $5.49USD
(unmarked) DC-DC 9V/12V to 5V 4A Mini Buck Module Converter Step Down Module Sale - Banggood Australia-arrival notice-arrival notice - pololu module D24V50F5 as noted by @wuxiekeji
I got mine from Core Electronics in Aus https://core-electronics.com.au/search/?q=d24v50f5 $36.40AUD - 30W 4A DC Auto Step Up/Down Converter 5V~30V to 9V 12V 19V 24V Boost-Buck Module $4.95USD
30W 4A DC Auto Step Up/Down Converter 5V~30V to 9V 12V 19V 24V Boost-Buck Module | eBay - 30/35W DC-DC 3A Auto Buck Boost Step Up/Down Power Supply CC CV Regulator Module
board labled - XY-SJV-4. Its from ebay but I cant find it there any more.
Items 3 and 4 will not power the Nano without persuasion. I purchased item 3, the 4A version because I expected to stress the unit a bit with GPU stuff.
As it stands today the base program (with some video analysis), when powered from desktop power supply only draws <1.3A for the whole setup including Arduino, all the servos, serial interface modules and so on.
So, so far we are not current constrained.
Item 3 has a shocking power on profile - rising to about 7.4V and taking 2 whole seconds to settle. No wonder the Nano has a fit and will not boot at all.
If you adopt the ‘switch before’ idea then it will have settled before powering the Nano - which it does but it still gets ‘Throttled messages’
Item 4 has an issue where it cant regulate quickly enough - it varies 4.08V to 5.68V about every 5ms
Item 2 suffers from under voltage to start with. This module has a constant 5V output its specs are 5V ± 4% so 4.8 to 5.2V
mine was delivering 4.978V on the scope it is OK, barely, rise time 8ms really good
but with the Nano’s range 4.75 to 5.25 (from the data sheet) it is just sailing too close to the lower limit for me
min max mean meter reads internal
unloaded 4.59 5.08 5.00 4.993
turning Nano on 4.68 5.02 4.91 4.965 Throttled
run main prog 4.68 5.04 4.88 4.955 4.672 to 4.712 Throttled!
Frankly I dont think ANY 5.0V module can work properly with the Nano. Even the plug pack starts at 5.11V
Item 1. This is the current winner. Its specs are 5.3V ± 1% so 5.247 to 5.353
I was worried about it being too high a voltage but looking internally its fine. Strangely it is also the smallest (less than an Aussie 5cent coin) and does not get hot at all.
Module out Plug_in Internal Internal-I(mA) scope p2p
unloaded 5.34 4.918
quintescent - idle 5.318 5.255 5.120 to 5.144 4.48-5.52 ~5.20 640mv (includes started tasks like serial2mqtt and mosquitto)
with visual studio open 5.325 5.265 5.160 to 5.176 416 to 424 4.52-5.40 ~5.01 880mv is a bit Throttled!
with main prog running 5.310 5.200 to 5.230 5.000 to 5.072 784 to 1000 NOT Throttled!
it also has an excellent power on rise time of 2.5ms
My next experiment is to add a capacitor to try and hold the voltage to eliminate some of the peak-2-peak issues these little module exhibit.
Trying with the bench power supply this is seen as about 85mv vs 880mv for the babies.
related references
from "System throttled due to Over-current."
and my previous post Issue with powering Jetson Nano from Boost-Buck converter
using advice on internal measurements Nvidia Jetson Nano / Xavier power monitoring | by ihwoo | Medium
somewhere in there it resolves to :-
sudo -s
cd /sys/bus/i2c/drivers/ina3221x
cd 6-0040
cd iio:device0
cat in_voltage0_input
Thanks - I hope this helps others
JC