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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

  • 0
    Prodigy 140 points

    please provide a reference image

  • 0 in reply to Yan Yu Tuan
    TI__Mastermind 18251 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 in reply to Robert
    Prodigy 140 points

    Hi Jonny

    Thank you for your response.

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

    Are there any other possibilities?

    Regards,

    Peter

  • 0 in reply to Yan Yu Tuan
    TI__Mastermind 18251 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 in reply to Robert
    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 in reply to Yan Yu Tuan
    TI__Mastermind 18251 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.