Level shifters
What matters in a level shifter is whether the bus pulls up or pushes, not how many channels you need.
BSS138/PCA9306 I2C shifters, TXB0104/TXS0108E auto-direction translators, 74LVC245/74AHCT125 buffers, and 12V-to-3.3V converters — matched to bus type and direction, not channel count.
- Use BSS138/PCA9306/QT-style shifters for I2C, Qwiic/STEMMA QT and other open-drain or slow bidirectional buses.
- TXB0104 and TXS0108E auto-direction parts only work correctly when their speed, capacitance and pull-up behavior match the bus — check the datasheet before assuming they are universal.
- 74LVC245 and 74AHCT125-style buffers handle deliberate one-way logic conversion; they are not suitable for I2C-style pull-up buses.
- The 12V-to-3.3V and 12V-to-5V converter modules handle industrial sensor signals that the BSS138 and TXB parts are not rated for.
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- Identify the signal first: I2C/open-drain, Qwiic/STEMMA QT, UART, SPI, GPIO, one-way LED data, or actual load switching.
- Choose the translator family for that signal type, not just for the number of channels.
- Check voltage rails, shared ground, channel count, direction pin or auto-direction behavior, pull-ups and bus capacitance.
- For I2C/Qwiic/STEMMA QT, prefer I2C-safe translators such as BSS138/PCA9306/QT shifters over TXB0108 or 74LVC245-style buffers.
- For faster push-pull signals, confirm clock rate, edge rate, cable length and capacitive load against the exact source page or datasheet.
- Do not use a logic level converter as a motor, relay, LED power or high-side load driver.
