Ruth Hendrix

Different Chips with the Same DIE ?

Discussion created by Ruth Hendrix Employee on Jan 19, 2006
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Posted: Wed Jan 19, 2005 3:56 pm    

I have some 68HC908QY1 CDW. These chips are the same as QY4, with the QY4 algorithm I can use the whole 4 K Flash memory and the AD channels are bonded too ( I checked this). So it seems that all these chips are equal. Maybe this changes in later mask sets. Maybe freescale will allways use the same DIE and label the Chips different only for marketing reasons. Has someone expierenced the same with other HC08 families ? The AP, GR, GZ or GT families could be good candidates.
I know that Freescale will nor give any garanty for this MCU´s to function properly, but for privvate use I thing ist ok.
Posted: Wed Jan 19, 2005 4:22 pm    
On page 175 of the data sheet it gives the differences in the QT1-QT4 ect, and a part number break down. Here is a link to the data sheet.
Posted: Wed Jan 19, 2005 4:52 pm   

I Know the differences, but I can definitely use 4K of Flash beginning at adress EE00 and the AtoD channels are working too on my QY1. So the only difference to the QY4 chips is that they are labeled different. I only had to declare the MCU as QY4 in my Project and the QY1 worked as QY4. 
Posted: Wed Jan 19, 2005 5:24 pm     
There are quite a lot of products like this and for home use I would have no problem using them as many will have full functionality on the bench/limited temp range. Production is a different mather though as they are tested differently and will not have the same product quality if used out of spec as the fully tested "real part".

I suspect that many/some of these devices will be cost reduced at some point in the future when they get round to it. I guess it will be volume driven.
Wed Feb 09, 2005 3:57 pm    
Many manufacturers do this with similar devices in a family of parts (it's been this way for years).

The difference is usually in the factory testing of them. They are only tested and qualified to the particular part number it is being sold as.

There is a good chance the extras will work, but you are taking your chances if you rely on it. Also, good luck when they make a rev change...

On the HC908 family, it's worth the extra few cents to buy what you really need.

Wed Feb 09, 2005 5:39 pm    
With the sample programme, if you only need a couple of them you won't even need to pay the extra few cents. It ain't worth the risk.