July 15, 2011 AT 8:23 pm

NEW PRODUCT – 8-channel Bi-directional Level Converter – TXB0108

Txb0108 Lrg

NEW PRODUCT – 8-channel Bi-directional Level Converter – TXB0108. 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.

Although one can use resistors to make a divider, for high speed transfers, the resistors can add a lot of slew and cause havoc that is tough to debug. For that reason, we like using 4050/74LVX245 series and similar logic to perform proper level shifting. Only problem is that they are only good in one direction which can be a problem for some specialty bi-diectional interfaces and also makes wiring a little hairy.

That’s where this lovely chip, the TXB0108 bi-directional level converter comes in! This chip perform bidirectional level shifting from pretty much any voltage to any voltage and will auto-detect the direction. Only thing that doesn’t work well with this chip is i2c (because it uses strong pullups which confuse auto-direction sensor). Its a little more luxurious than a 74LVX245 but if you just don’t want to worry about directional pins this is a life saver!

This breakout saves you from having to solder the very fine pitch packages that this chip comes with. We also add 0.1uF caps onto both sides and a 10K pull-down resistor on the output enable pin so you can use it right out of the box!

In stock and shipping now!


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5 Comments

  1. Paul J. Ste.Marie

    Woo hoo! Very nice indeed! Beats the usual ugly hacks

    Merge this into an XBee shield and you’re rocking.

  2. andyx (@Enzyox)

    Data sheet is here.

    http://pdf1.alldatasheet.com/datasheet-pdf/view/169210/TI/TXB0108.html

  3. Great idea, and a cool chip. I’m curious if you’ll be providing breakout to the TXS0102, which is intended for applications like i2c/1-wire.

  4. we will have the txs0102 shortly, we just got the prototype in and are testing it now (there is no ETA, however)

  5. You mention that this chip does not work well for I2C.

    I have also found that it does not work well with some servos, specifically a couple models of the GWS Nano servos. It has worked well with others.

    You can get it to work with these servos by putting a resistor inline with the signal (to reduce the strength of the pullup that appears to be in the servo). I used a 10K 1/8W resistor because it was handy, but the ideal is supposed to be around 4.7K or 5.1K.

    Note that you don’t need 5v to control these particular servos. I’ve gotten them to work with around 2.5v (I forget the exact lower limit in my test).

    It’s just something else to consider when using these chips.

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