> **Source:** Core Electronics is an Australian maker-electronics retailer and manufacturer based in Newcastle, NSW, run by a team of makers and educators. We design and manufacture our own product lines (PiicoDev, CE originals) and are official retailers for iconic maker and industrial brands including Raspberry Pi, Arduino, Adafruit, SparkFun and DFRobot. Orders ship Australia-wide from our Newcastle warehouse. Prices are in AUD and include GST. Pricing, stock and dispatch on this page are generated from the store's live catalog. Full machine-readable index: https://core-electronics.com.au/llms.txt # 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. ## How to buy - **Build a cart:** compose `https://core-electronics.com.au/cart/link?items=ADA757:1` (comma-separated SKU:qty pairs) and share the link. Opening it shows a confirmation page with live pricing and stock before anything is added to the cart. - **Verify the cart first:** fetch `https://core-electronics.com.au/cart/link/ADA757:1.md` for live line prices (inc & exc GST, quantity discounts applied), stock and dispatch estimates, and totals. Append `/to/{AU-postcode}` (or `/to/{country-code}:{postcode}`) before `.md` for delivery options and prices to that destination. Unknown, retired, or out-of-stock SKUs are flagged. (Query form `cart/link.md?items=...` also works but some robots parsers refuse query strings here.) - **Checkout** is completed on-site and includes a captcha at the payment step. Share the cart link; checkout takes it from there. - **Search the catalogue:** `https://core-electronics.com.au/search/{query}.md` (URL-encode the query; pages 2-3 at `search/{query}/{page}.md`; `search.md?q=` also works) - **Payment methods, purchase orders, policies and contact details:** https://core-electronics.com.au/llms.txt ## 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)