andrewm

AD5781 Eval board bug that can kill the board   

Discussion created by andrewm on Jun 28, 2016

AD5781 18 bit dac Eval board bug that can kill the board   

 

A heads up to anyone that purchases the AD5781 Eval board, about USD 150 ;

 

It has jumpers that allow  you to set the VccIO to 3v3,

     so that it can interface to none 5v logic , whilst running the Vcc to the AD5781 at 5v.

 

If you do this, you can blow the chip, as I have done, due to the design of the eval board.

 

Hunt through the schematic and you will notice that the digital IO to the ADC5781 is pulled up to Vcc ( 5v ) not VccIO ,

 

   QED, one is applying 5v to the digital inputs of the AD5781 via these pull ups on the ad eval board, that is out side the recommended range unless you have VccIO at 5v .

 

Analog Devices recognize this, and say they are looking at an eval  board re spin,

 

     but wont replace our blown board nor the two days we have spent trying to get it to work before we found this mistake on the analo devices eval board.

 

hope no one else does this.

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