Learning Cycle in Bq20z95

Deepak Bansal

Expert 2395 points

When do a valid learning cycle is considered in Bq20z95. Is it when during charging COV sets & discharging CUV sets.

over 14 years ago

0 Jason Blackman over 14 years ago

TI__Genius 14015 points

Deepak,

You don't need to go all the way to the COV and CUV limits for a learning cycle. As long as the change in capacity before and after charge/discharge is at least 90% of the Design Capacity, Qmax will be able to update. This is only necessary for the first cycle. Subsequent cycles will allow Qmax updates if at least 37% of Design Capacity is passed during charge/discharge.

The document slua364 explains in more detail about Impedance Track (http://www.ti.com/lit/an/slua364/slua364.pdf)

Regards,

Jason

0 Deepak Bansal over 14 years ago in reply to Jason Blackman

Expert 2395 points

Thanks Jason for your reply.

1. Why is it written in datasheet of z95 that it require no learning cycle. When I have to give it a learning cycle to update Qmax & Ra Table. Is it after creating golden pack?

2. What is max design cap be used 32767 or 65535mAH. In datasheet it is 65535mAH. However max Qmax can be +32767.

Regards

0 Jason Blackman over 14 years ago in reply to Deepak Bansal

TI__Genius 14015 points

Deepak,

I believe what the datasheet is referring to is that there is no full charge/discharge cycle required during the lifetime of the pack to keep the gauging accurate.

The max design capacity is 32767mAh, not 65535. I will talk to someone about getting the documentation updated. I apologize for the confusion.

Regards,

Jason

0 Deepak Bansal over 14 years ago in reply to Jason Blackman

Expert 2395 points

Then what golden pack do. Does it increase accuracy of pack when packs are in production stage. I have one of pack with 1% max error. How to read golden pack from it & write to other packs.

0 Jason Blackman over 14 years ago in reply to Deepak Bansal

TI__Genius 14015 points

A golden pack is basically one that you've already done the initial learning cycle on to get Qmax updated, and configured the data flash to be the way you want it. Then you take the ROM and DFI files to use with your other packs. This process is meant to mitigate production time. More is explained in the document, 'Data Flash Programming and Calibrating the bq20zxx Family of Gas Gauges' http://www.ti.com/general/docs/lit/getliterature.tsp?literatureNumber=slua379b&fileType=pdf

Section 2 specifically explains how to create the golden pack and write it to other packs.

Regards,

Jason

Power management

Power management forum

Learning Cycle in Bq20z95