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Unable to do complete RESET on BQ27501

Other Parts Discussed in Thread: BQ27501


I have come across a strange issue regarding RESET on the BQ27501.

I am using the EVSW connected to pcb which we have designed, containing a bq27501.

I have 2 battery packs with completely diiferent chemisteries. They do NOT however  have RID sense resistors.

I must therefore simulate these sense resistors by manually utilizing 2 different resistors which are enabled based apon the voltage of the battery pack.

Lucky for me, these 2 battery packs function in 2 different voltage areas and therefore it is relatively easy to distinguish the two.


What I do is...

1. Measure the voltage of the cell

2. Based on this value I enable an output from a FPGA to activate the correct resistor.

3. Reset the BQ27501

This is where the issue occurs.......

After resetting the device, it will not choose the correct battery profile.

I have to reset it at least twice before it will come up with the correct Full Charge Capacity

The strange thing is that it seems to be reseting ie. I see many of the values change to 0 or dissapear

The LU_PROF flag indicates that the correct profile is in use, however the Full Charge Capacity is the incorrect previous value.

Could anyone please tell me why this is happening?

Even removing the power to the IC does not change the value to the correct one ie. I feel it has something to do with copying of FLASH to RAM after a reset???


Best regards

   Roger Yttervik

  • Roger,


    Couple questions I want to ask:

    1. How the two different type of battery chem ID being determined?

    2. How the learning cycle being done on each batteries?

    3. What RID voltage level is set or simulated? 

    4. can you share schematic?