Fair enough. I already have some 0.1uF ceramic capacitors handy which the sparkfun hookup guide recommends. I found a few notes saying its possible to power “a few” LEDs from the Pi 5v pin and I think my requirement would only be for 0.12A but I cant seem to find any spec saying the Pi Zero w 1.1 can deliver this - or any spec from Raspberry Pi saying what the max allowable draw is.
If I just buy the logic converter, and power the LEDs from the 5v pin with a 220-470 ohm resistor on the data line am I good to go? Otherwise I can just hookup a double phone charger and use one socket for the Pi and the other socket for the LEDs with a ripped up USB cable?
Your estimate of 120mA consumption is a good base to start. An important aspect of this question is what exactly your supply voltage is. I’m assuming you’re powering the Pi with a USB cable given you want to use the 5V, but there are different USB types of course.
The bare board current consumption of the Pi Zero W is listed as 150mA, because of this low power you can probably get away with this. See below the current draw capabilities of different USB protocols.
So even using USB 2.0 you should have about 300mA to play with technically. I would avoid going near that limit, our recommendation is obviously to use an external power supply. But you should absolutely be able to get away with powering a couple of these from the 5V on the Pi.
Additionally, make sure you’re not powering these directly from GPIO, the current draw capabilities of the GPIO pins themselves are nowhere near powerful enough to supply the NeoPixels.
The first table is in the RPi documentation on Github. There’s a specific section for “Power Supplies” here’s a link:
In regard to the USB power draw capabilities, Wikipedia has a large list of the different PD modes here:
In the section marked “Power”.
Though this a bit too in-depth, as most devices will reconfigure themselves to be capable of drawing whichever is the fastest possible. For example, most modern phones will configure themselves to use fast-charge when available.
For the USB current draw table I posted above, I used this website/article, which details the functionality of the PD protocol used on modern USB devices.
