VREF Error

Chris Pennekamp 6 years ago updated by Edward Polzin 6 years ago 3

I was hoping to get some feedback on an error I am encountering. One of our VREF channels is acting up an our MC43 controller.  As soon as VBB is greater than 14.0 volts, the Vref goes immediately to 0.0v and throws an error. If VBB drops back down below 14v, the error goes away. The only thing on this Vref is a position sensor (500-4500mv) going into a VIN.  Any thoughts on what could be causing this? I'm happy to provide more information if necessary, but I'm not sure what else would be of help. 



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Are you using a variable power supply for a bench test? 

It is a guess, but if the power supply is on the limit, maybe there is a dip in supply? 

I have seen MC43 VREF errors when dropping the supply extremely low, just below 6 V supply. 

Gustav, we are not using a variable power supply. This is on a vehicle. At the time of the error the 12v system was connected to 12v charger. The error is only when the input voltage goes above 14v. When it is below that, it is fine and the VREF looks normal. We have not had a chance to troubleshoot further as the car is not near us, but when we do get access to it, we have a few other things we will check. Thank you so much for the reply and if you have any more ideas I would love to hear them.



Are you using the battery charger as a power supply for the system?  

I have seen cases where this has been attempted and as soon as the system draws any significant load, the charger output will drop out.  Going above 14V generally may cause the system to draw more current, hence, dropping supply of the module below the accpetable operating threshold.  If you are using a battery charger, please try while a good battery is connected as well.  Or use a benchtop power supply.