Driving Neopixel SK6812 LEDS using 3.3V logic

Thread Starter


Joined Dec 17, 2015
I have a prototype PCB where multiple SK6812 RGB LEDS are driven using a SN74AHCT125DR as a logic level shifter. The CPU is a SAMD21G18 running at 3.3V. The 3.3V PIN from the CPU is connected to the "1A" input of this SN74AHCT125DR chip. The "1Y" output is connected to DIN of the first Neopixel led. The Neopixel leds are running of a 5V supply.

While this all works well I'm looking at ways to decrease the overall PCB size. The SN74AHCT125DR is quite big while only 1 out of the 4 input/outputs are used. So I wonder if I can't just replace it with a BSS138 FET and 2 resistors like this:


This should be shifting the voltage from 3.3v to 5v too but I'm not sure if this circuit is fast enough for driving the Neopixel leds?
Any ideas?