BQ28Z610-R1: BQ28Z610-R1 - Authenticity of Lifetime Record

Yan Yu Tuan

Prodigy 140 points

Part Number: BQ28Z610-R1

Hi TI team

I have a question regarding the LIFETIME record.

My customer, in a normal storage environment, has the LIFETIME record showing a low temperature of -74 degrees.

I've checked the NTC and found no issues.

Can you tell me other possible reasons?

Could it be caused by noise?

Regards,

Peter

11 months ago

0 Yan Yu Tuan 11 months ago

Prodigy 140 points

please provide a reference image

0 Jonny 11 months ago in reply to Yan Yu Tuan

TI__Mastermind 19701 points

Hello,

At some point the temperature had to dip to -74 degrees C for this to be logged under the minimum cell temp lifetime data. If the cell temperature never dipped below this, then a possible explanation could be that there was an open circuit, causing the recorded temperature to dip.

Regards,

Jonny.

0 Yan Yu Tuan 11 months ago in reply to Jonny

Prodigy 140 points

Hi Jonny

Thank you for your response.

It's unlikely for the environmental temperature in Japan to be below -72 degC.
I opened the NTC circuit, and it displayed -52 degC (please refer to the image).

Are there any other possibilities?

Regards,

Peter

0 Jonny 11 months ago in reply to Yan Yu Tuan

TI__Mastermind 19701 points

Hello Peter,

Another possible cause of this is if somehow the TS pin got biased to a higher voltage than the reference voltage, causing the temperature being reported to be a very low and unrealistic value.

Regards,

Jonny.

0 Yan Yu Tuan 11 months ago in reply to Jonny

Prodigy 140 points

Hi Jonny

The reference voltage for TS from within the IC.

Could this be misunderstood as a problem with the IC?

Regards,

Peter

0 Jonny 11 months ago in reply to Yan Yu Tuan

TI__Mastermind 19701 points

Hello Peter,

My apologies for the confusion, I was referring to a bias at the TS1 pin. If there was somehow a voltage applied to the TS1 pin, then this could cause the device to measure a lower temperature than it should be. Since you are using an NTC, if the resistance goes up then the temperature will go down, so a higher voltage seen at the TS1 pin would lead the gauge to believe that the resistance is higher and therefore the temperature is lower. Additionally, for the gauge to report to the lifetimes, it just has to see this value for a very short period of time.

Regards,

Jonny.

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BQ28Z610-R1: BQ28Z610-R1 - Authenticity of Lifetime Record