# 4-channel I2C-safe Bi-directional Logic Level Converter - BSS138

**Type:** Product page · **SKU:** ADA757 · **Brand:** [Adafruit](https://core-electronics.com.au/brands/adafruit-australia)
**Page:** https://core-electronics.com.au/4-channel-i2c-safe-bi-directional-logic-level-converter-bss138.html ([markdown](https://core-electronics.com.au/4-channel-i2c-safe-bi-directional-logic-level-converter-bss138.html.md))

Because the Arduino (and Basic Stamp) are 5V devices, and most modern sensors, displays, flash cards and modes are 3.3V-only, many makers find that they need to...

## Pricing

- **Price:** $7.40 (inc GST) — $6.73 AUD, exc GST
- **Quantity discounts:** 10+ $6.53 (exc GST) · 50+ $6.39 (exc GST)

## Availability & dispatch

- In stock, ships same business day if ordered before 2PM (Australia/Sydney).
- We can dispatch 12 today, and up to 500 more in 8–12 days.

## Description

Because the Arduino (and Basic Stamp) are 5V devices, and most modern sensors, displays, flash cards and modes are 3.3V-only, many makers find that they need to perform level shifting/conversion to protect the 3.3V device from 5V.

We do have some other handy level shifters in the shop, from the [DIP 74LVC245](https://core-electronics.com.au/74lvc245-breadboard-friendly-8-bit-logic-level-shifter.html) to the fancy [bi-directional TXB0108](https://core-electronics.com.au/8-channel-bi-directional-logic-level-converter-txb0108.html). However, neither of these are happy to work with I2C, which uses a funky pull-up system to transfer data back and forth. This level shifter board combines the ease-of-use of the bi-directional TXB0108 with an I2C-compatible FET design following NXP's app note.

This breakout has 4 BSS138 FETs with 10K pullups. It works down to 1.8V on the low side, and up to 10V on the high side. The 10K's do make the interface a little more sluggish than using a TXB0108 or 74LVC245 so they suggest checking those out if you need high-speed transfer.

While Adafruit designed it for use with I2C, this works as well for TTL Serial, slow <2MHz SPI, and any other digital interface both uni-directional and bidirectional. Comes with a fully assembled, and tested PCB with 4 full bidirectional converter lines as well as 2 pieces of 6-pin header you can solder on to plug into a breadboard or perfboard.

## Technical Details

- [BSS138 Datasheet](https://core-electronics.com.au/attachments/localcontent/BSS138_12397c2dfcd.pdf)
- [EagleCAD PCB files on GitHub](https://github.com/adafruit/4-Channel-Level-Shifter-PCB)
- [Fritzing library](https://github.com/adafruit/Fritzing-Library)

[The newer NXP app note explaining how it works](https://core-electronics.com.au/attachments/localcontent/AN10441_53707795f15.pdf) (the older [Philips version of the app note](https://core-electronics.com.au/attachments/localcontent/an97055_77105d40135.pdf) is also worth a read)

 ![](https://core-electronics.com.au/attachments/localcontent/rohs_icon_8216055e11.jpg)

## Guides for this product

- [How to Use a Logic Level Shifter/Converter](https://core-electronics.com.au/guides/digital-electronics/how-to-use-logic-level-shifters-converters/)

## Videos for this product

- [Logic Level Converters for Particle](https://core-electronics.com.au/videos/logic-level-converters-for-particle)

## Images

- [Product image 1](https://core-electronics.com.au/media/catalog/product/7/5/757-03.jpg)