XMega128A3U Brown-out detection voltage level

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Hi, 

 

I need some help with the Atmel XMega128A3U.

I have found some strange behaviour with the brownout detection voltage level... 

 

The latest version of the Xmega128A3U datasheet on pg.: 113 (link) says the BOD voltage level ranges from 1.6V to 3.0V. But if I program the FUSE bits to 3.0V  - with Atmel studio 7 - after programming, the device stays in reset state with 3.3V supply voltage, and only starts when I increase the supply voltage to 3.55V

 

I did some research and I found that in the Xmega128A3 datasheet on pg.: 109 (link) says the  BOD voltage level ranges from 1.6V to 3.4V and the binary coded voltage levels matches the real ("measured") voltage levels with my Xmega128A3U CPU.... A have measured every possible BOD voltage settings, and all of them matching the levels in the Xmega128A3 datasheet.. but my CPU is Xmega128A3U! 

 

I have attached a photo about my CPU's device marking, which says this is a "ATXMEGA128A3 AU 1710" 

 

My question is, is there a mistake in the datasheet, or the device marking is wrong on my IC? 

 

Thank you! 

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OMG! :( :( :(

I have just noticed that the "AU" stands for the case, and not for marking the new version of the CPU, which has USB support... 

(topic can be deleted...)

 

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The AU manual URL results in a 404.

AU manual : http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-8331-8-and-16-bit-AVR-Microcontroller-XMEGA-AU_Manual.pdf

AU datasheet : http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-8386-8-and-16-bit-AVR-Microcontroller-ATxmega64A3U-128A3U-192A3U-256A3U_datasheet.pdf

datasheet page 105 - note the BOD has a range (min .. typ .. max) so for a 3.0V typ BOD would be 3.1V max. estimated.

 

A datasheet : http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-8068-8-and16-bit-AVR-XMEGA-A3-Microcontrollers_Datasheet.pdf

BOD level 7's is 3.49V typ with 3.56V max estimated (close to your observed 3.55V)

IIRC, DocJC had a similar issue that he solved by raising Vcc above the BOD threshold then resetting the BOD threshold to where he wanted it.

 


http://www.microchip.com/wwwproducts/en/atxmega128a3u

http://www.microchip.com/wwwproducts/en/atxmega128a3

 

"Dare to be naïve." - Buckminster Fuller

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How funny.

 

I just discussed the Xmega's BOD in another Thread.

 

And Good Memory!

The BOD is the only way I know of to reversibly "brick" an Xmega.

 

IIRC the BOD threshold voltages have a rather wide in spec range for each of the stated voltage levels.

I'm not n the right computer to look at the data sheet, but it is buried within either the Electrical Spec's table, or the many graphs at the end of the data sheet.

 

JC