I2C level changing IC for ~$6

I came across this IC that appears to be a good solution to interfacing Picaxe to I2C bus devices of lower voltage. The device is ADuM1250 and available from RS.

http://australia.rs-online.com/web/p/interface-misc/0412810/?searchTerm=ADuM1250&relevancy-data=636F3D3226696E3D4931384E4B6E6F776E41734D504E266C753D656E266D6D3D6D61746368616C6C7061727469616C26706D3D5E5C772B2426706F3D313326736E3D592673743D4D414E5F504152545F4E554D424552267573743D4144754D313235302677633D424F544826

Does anyone have any comment as to its suitability? I am looking at buying one to try between Picaxe and a magnetometer. It is surface mount so might be a bit fiddly to connect.

Fred

The AduM1250 should work as an i2c bus level shifter – after all that is part of the design feature.


However, unless you need the isolation and hot-swap capabilities you can easily just use two 2N7000 (or similar) FET’s.
Both the AduM1250 (see datasheet figure 9) and FET options required two pull-up resistors on both sides of the devices for the i2c bus to function.

For the FET approach, which is based on a technical paper on level shifting by Philips/NXP, Sparkfun do a small module inclusive of the SMD transistors and necessary resistors for US$1.95 in a “breakout” format suitable for breadboards. See here: http://www.sparkfun.com/products/8745
In Australia (NSW), Littlebird Electronics sell the Sparkfun product for AUD$2.21.
See here: http://littlebirdelectronics.com/products/logic-level-converter


I have succesfully used the two x 2N7000 FET approach with TO-92 case devices for i2c bus level shifting.

Thanks for your thoughts. I just thought that it was another option for consideration. I have looked at using the 2 FETs as they are less than 20c each from RS but I have to lash out and get 5 of them. They are not available of the shelf in Perth so needs to be online purchase. Hardly seems worth the postage (free) for such a small order. I was looking for something to make it worthwhile when I came across this device.

fred

Altronics, Perth's local PICAXE reseller, also sells 2N7000s for 47c each (33c in quantities > 25). www.altronics.com.au

freddagg said:

Thanks for your thoughts. I just thought that it was another option for consideration. I have looked at using the 2 FETs as they are less than 20c each from RS but I have to lash out and get 5 of them. They are not available of the shelf in Perth so needs to be online purchase. Hardly seems worth the postage (free) for such a small order. I was looking for something to make it worthwhile when I came across this device.

fred

Click to expand...

Altronics in Perth have the 2N7000 in the TO-92 package
http://www.altronics.com.au/index.asp?area=item&id=Z1555

But avoid Jaycar in this instance at 3 times the price
http://www.jaycar.com.au/productView.asp?ID=ZT2400

Also, the Sparkfun breakout board I mentioned earlier is available in Perth from Robotgear for $2.42 (order online but only mail delivery)
http://www.robotgear.com.au/Product.aspx/Details/500

For your future reference, keep Futurlec in mind for on-line ordering with generally competitive pricing.
http://www.futurlec.com.au/

2N7000 at AU$0.10 ea and a handful of parts mailed from their warehouse (in Thailand) for AU$4.00.
7 to 14 days delivery for regular mail.

Thanks.

I will forever be amazed at the knowledge of "how to" and "where from" that is available from the forum.

These sites have been added to my Favourites.

I have received my 2N7000 so now have to get time to modify my board and use them.

Fred