Adafruit
4-channel I2C-safe Bi-directional Logic Level Converter [BSS138]
This bi-directional logic level converter from Adafruit uses 4× BSS138 FETs with 10K pull-up resistors to safely shift signals between different voltage leve...
This bi-directional logic level converter from Adafruit uses 4× BSS138 FETs with 10K pull-up resistors to safely shift signals between different voltage levels. Unlike many level shifters, this design is fully compatible with I2C's open-drain pull-up signalling, following NXP's recommended application circuit.
The converter works from 1.8V on the low side up to 10V on the high side, making it versatile for interfacing between 3.3V sensors and 5V microcontrollers, or any other voltage combination in that range. It also works with TTL serial, slow SPI (<2MHz), and other uni-directional or bi-directional digital interfaces.
Key Features
- I2C Compatible – BSS138 FET design works with I2C's pull-up signalling
- 4 Bi-Directional Channels – Level shift 4 signals simultaneously
- Wide Voltage Range – 1.8V to 10V, any combination of low and high side
- 10K Pull-Ups Included – Built-in on each channel
- Multi-Protocol – Works with I2C, TTL serial, slow SPI, and other digital interfaces
Specifications
- FET – BSS138 (×4)
- Pull-Up Resistors – 10K per channel
- Low Side Voltage – 1.8V to 3.3V (typical)
- High Side Voltage – Up to 10V
- Channels – 4 bi-directional
- Supported Protocols – I2C, TTL serial, slow SPI (<2MHz), GPIO
Ideal For
- Interfacing 3.3V sensors with 5V Arduino boards
- I2C bus level shifting
- Mixed-voltage prototyping
- Any project requiring safe voltage level conversion
Package Contents
- 1× Assembled and tested 4-channel level converter PCB
- 2× 6-pin headers (for breadboard use, soldering required)
Jargon buster
Plain-language definitions for the technical terms used above.
- GPIO
- General-purpose input/output pins are microcontroller pins you can set in software to read signals, switch devices on and off, or connect to peripherals. The number of GPIO pins matters because it limits how many buttons, LEDs, sensors, and other parts you can wire directly to the board.
- Headers
- Rows of metal pins used to plug a module into a breadboard or connect it with jumper wires. Pre-soldered headers make the module easier to use straight away without needing to solder the pins yourself.
- I2C
- I2C is a two-wire communication bus used by many sensors and small modules. It matters because several I2C devices can share the same two wires, but each device needs a compatible address and your controller must support I2C.
- PCB
- A printed circuit board is a rigid board with copper tracks that connect electronic parts without loose wires. For this kit, the PCBs also form the airplane shape, so they are both the circuit base and part of the finished model.
- SPI
- A fast serial communication bus often used for displays, memory cards, and sensors. It matters because SPI devices need specific pins for clock and data, plus a separate chip-select line for each device.
- TTL serial
- A simple serial data connection that uses microcontroller logic-level signals rather than computer RS-232 voltage levels. It matters because the camera can connect directly to many microcontroller pins or a USB-to-TTL serial adapter, but not safely to an old-style RS-232 port without conversion.
- UPS
- An uninterruptible power supply is a battery-backed power system that keeps a device running when external power is unplugged or fails. For an embedded computer, it helps prevent sudden shutdowns that can corrupt files or interrupt a project.
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