EVAL-AD7195ASDZ EXC- is not working properly

Question

Hi, 
 I am facing following problem: the EXC- does not work with load cell connected to the EVAL-AD7195ASDZ, there is effectively no square wave on this output 
 I have two such boards and both are having the same failure. 
 I am connecting scale with HBM load cell (I am having 2 of them and checked every combination). 
 I am having also some of the old eval boards (AD7195EBZ) and each of them works properly, the excitation behaves as should: I am getting symmetrical square wave with the scale connected 
 
 EXC- is red, EXC+ is yellow, load cell connected 
 
 EXC- is red, EXC+ is yellow, no load cell

mmad · Accepted Answer

Hello Francis, 
 I found the reason, the 6 wire load cell uses REFIN pins. 
 Those pins are hard connected to positive ref voltage source and ground. 
 That's strange because you equipped the board with AC excitation power stage, so at least an info in wiki should be given, how to use it, and 
 an option to disconnect the pins should be provided. 
 The AC excitation works properly, when I removed the very small R20 and R22 components. 
 BR, Marek)

Popular Forums

Product Forums

Application Forums

Design Center Forums

Highlighted Webinar

Places

Libraries

Upcoming Learning & Events

Challenge Yourself!

What's Brewing

Places

Resources

Visit ContentZone

The Latest Read

New Release

Recent Technical Insights

Products Mentioned

Associated Drivers

Thread Details

EVAL-AD7195ASDZ EXC- is not working properly

Edit Notes