# Do NOT use BSS138 for logic level shifting (too slow!)

**URL:** <https://wled.discourse.group/t/do-not-use-bss138-for-logic-level-shifting-too-slow/6054>\
**Category:** Hardware\
**Created:** [October 6, 2022, 4:29am UTC](https://wled.discourse.group/t/do-not-use-bss138-for-logic-level-shifting-too-slow/6054 "2022-10-06T04:29:48Z")\
**Posts on this page:** 1\
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**Author:** ![divsys](https://avatars.discourse-cdn.com/v4/letter/d/a3d4f5/32.png) [@divsys](https://wled.discourse.group/u/divsys)\
**Post date:** [October 6, 2022, 5:11am UTC](https://wled.discourse.group/t/do-not-use-bss138-for-logic-level-shifting-too-slow/6054/2 "2022-10-06T05:11:57Z")

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On the level shifter:

The basic data stream for WS281x series is less than 1Mhz, but with some fairly tight timing requirements for the Hi and low pulses - down in the 150ns range. That means the ~2Mhz speed of the BSS138 device might not deal well with all of the data waveform, especially the faster bits.

Any of the 74AHCTxxx devices will do a better job ('08,'32,125,245), they’re cheap, fast and reliable.  
If the size of the package is too much, the 74lvc2t45 is a tiny package with 2 independent shifters.  
Much faster than the MOSFET and still very cheap.

On the scope:

If you’re looking for a scope to properly visualize the actual data stream, you need to start at the 10Mhz devices at minimum. When dealing with pulse widths of 100-150ns you’re talking 10Mhz, and more bandwidth (that means more than 10Mhz) is always better.

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