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Original question:

BQ25886: Question about temperature test result

BQ25886: Question about temperature test result: ver 2

Satoshi
Guru 19645 points
Part Number: BQ25886

I apologize for delayed update on below thread.

I got customer condition from you requested, please see below.

Measured current value with a DMM: ICHG is 414mA and IPRECHG is 40mA

⇒IPRECHG / ICHG = 0.0966 (About 1/10)

Please let me confirm about above operate is normal or abnormal.

Best regards,

Satoshi

  • 0
    TI__Genius 10385 points

    Satoshi-san,

    Pre-charge and termination current is 1/10 of the fast charge current. This is expected behavior.

    Source: 8.3.7.1 Autonomous Charging Cycle

    I hope this resolves your issue,

    Ricardo

  • 0 in reply to Ricardo
    Guru 19645 points

    Ricardo-san

    Thank you for reply,

    I think that first charge current will become ICHG / ICHGSET : 20% by attached below (Datasheet Page 21).

    But measured ICHG was 414mA, it is 40%. (ICHGSET is set 1A) 

    I hope to clarify why ICHG became 40% of ICHGSET. 

    When my thinking found misunderstood, please let me know correct definition.

    And, is there cause of trigger that become ICHGSET ×40%?

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Genius 10385 points

    Satoshi-san,

    In your previous post you said ICHGSET is 1.5A and now you say it is 1A. Which is it?

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    Guru 19645 points

    Ricardo-san

    I apologize for confuse, previous information was mistaken.

    Correct status is ILIM: 1.5A and ICHGSET: 1A.

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Genius 10385 points

    Satoshi-san,

    Your measured value when in JEITA "cool" is 414 mA. Please confirm you are in JEITA cool by providing a voltage measurement for TS and REGN.

    Also provide a current measurement for ICHG when in JEITA "normal." Please confirm you are in JEITA normal by providing a voltage measurement for TS and REGN.

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    Guru 19645 points

    Ricardo-san

    Please see below about condition of JEITA normal.

    ・V_ICHGSET: 0.731V

    ・TS～REGN voltage: 2.145V （TS～GND voltage: 2.875V, REGN～GND voltage: 5.04V）

    Customer could not measure JEITA cool TS～REGN voltage because temperature chamber is not ready now. 

    By the way, customer is already confirmed temperature profile threshold: JEITA cool switched 5℃ and 15℃, JEITA hot switched 45℃ and 58℃. 

    They guess that TS voltage is normal operating.

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Genius 10385 points

    Satoshi-san,

    I did not ask for V_ICHGSET. I asked for ICHG.

    Please provide the correct parameter.

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    Guru 19645 points

    Ricardo-san

    I apologize for my mistake.

    I confirmed customer's measurement again.

    ICHG is 938mA (start)

    By the way, IPRECHG is 125mA.

    ※Condition is JEITA "normal".

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Genius 10385 points

    Satoshi-san,

    I will verify this on my BQ25886EVM and have an update for you by Friday (Dallas time).

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    Guru 19645 points

    Ricardo-san

    Thank you for reply,

    I understood your schedule.

    I looking forward your update.

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Genius 10385 points

    Satoshi-san,

    From my observations I am seeing the behavior described in the datasheet. That is to say I am seeing a 20% of the ICHG value in JEITA cool. This is not aligned with the behavior you are seeing.

    I tested this on the BQ25886EVM and took detailed notes on my configuration. That I have shared below. Please review this configuration carefully and feel free to ask me elaborate further if I missed anything.

    Measured on BQ25886EVM:

    VBAT: 7.6 V

    VSET setting: 8.4 V

    V_ICHGSET: 427 mV

    D+ = D- = 0 V shorted to each other for maximum input current

    ILIM = 0 V shorted to GND for maximum input current

    R_TH measured from leads: 22.15kohm*

    *This is the resistor value I used to induce the JEITA cool condition in place of the thermistor. To induce JEITA normal condition a 10k resistor soldered to the EVM was used.

    ICHG_25C: 1039 mA

    ICHG_5C: 210 mA

  • 0 in reply to Ricardo
    Guru 19645 points

    Ricardo-san

    Thank you for evaluate,

    Would you evaluate again for arrange the same condition as customer below?

    (Battery is empty, and a few the other changed)

    ・VBAT: 6.3V(start) ～ 7.0V　

    　※Battery condition is empty

    ・VSET setting: 8.2V

    ・V_ICHGSET: 0.7V

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Genius 10385 points

    Satoshi-san,

    I need you to measure the resistance on ICHGSET to GND. Our settings appear significantly different.

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    Guru 19645 points

    Ricardo-san

    I confirmed measure the resistance on ICHGSET to GND, it was 5.87kΩ.

    I also thinking that significantly different, I confirming the reason and improvement plan.

    By the way, is ICO setting relate for charge current on JEITA Cool?

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Genius 10385 points

    Satoshi-san,

    So if R_ICHGSET is 5.87k then ICHGSET is 1.5A not 1A as you have previously told me. Please align with your customer on their desired settings as there appears to be miscommunication.

    More precisely ICHGSET is 1.54A, so for JEITA cool you can expect 20% of 1.54A to be your charge current. It should approximately be 308 mA.

    Please note this does not account for the accuracy of your R_ICHGSET resistor, the resistance of introduced by your layout, or the accuracy of the charge current regulation loop. 

    The ICO algorithm is one of the mechanisms responsible for setting the input current limit. It is in effect regardless of JEITA status.

    Thanks,

    Ricardo 

  • 0 in reply to Ricardo
    Guru 19645 points

    Ricardo-san

    I confirmed to customer, correct ICHGSET is 1.5A, not 1A.

    I apologize for confuse. 

    Thank you for advice, I will continue to confirm customer condition: accuracy, layout, loop, etc.

    By the way, please let me know about situation of ICHG_5C: 210mA you measured.

    For example, threshold for CV discharge to battery off (empty), or minimum charge current, etc.

    (Customer's situation is CC charging on battery is empty)

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Genius 10385 points

    Satoshi-san,

    I provided all of my parameters in my reply. At the time I assumed ICHG was set to 1A, so a 210 mA charge current in JEITA cool is expected behavior. There is no issue here.

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    Guru 19645 points

    Hi Ricardo,

    It took a while, I got customer's evaluating condition.

    Measured resistance on ICHGSET to GND is 5.87kΩ include the other condition (accuracy, layout, etc).

    How is the accuracy range of 20% JEITA cool?

    Is 414mA within acceptable range for ICHGSET: 1.5A × 20% ±??% by JEITA cool? 

    By the way, as a test customer changed R_ICHGSET 5.87kΩ to 270Ω(ICHGSET: 70mA), measured results was about 400mA.

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Genius 10385 points

    Satoshi-san,

    I will look into the accuracy of the JEITA setting next week and will follow up on Wednesday.

    It is highly unusual that your customer is observing this and it is not expected behavior. Do you have anymore information on this?

    Best Regards,

    Ricardo

  • 0 in reply to Ricardo
    Guru 19645 points

    Hi Ricardo

    Thank you for your following,

    I looking forward your update.

    Sorry for the lack of information, customer additional information is not update now.

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    Guru 19645 points

    Any update on this?

  • 0 in reply to Satoshi
    TI__Genius 10385 points

    Satoshi-san,

    After consulting with my colleague it is expected for there to be no error added by the JEITA reduction. That is to say:

    1.54A * 20% * +/-25% is the acceptable current range. Your observation of 414 mA is just barely out of the acceptable range at 26%. Please remind me, house this current is being measured?

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    Guru 19645 points

    Hi Ricardo

    Thank you for support,

    Yes, 414mA current is measured data by customer.

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Genius 10385 points

    Satoshi-san,

    How did they measure this result? Is there a potential error in the measurement?

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    Guru 19645 points

    Hi Ricardo

    These result is measured by multimeter: 414mA.

    By the way, ICHGSET~GND resistance value changed the other range of "5.87kΩ~270Ω", COLD ICHG was also keep 414mA.

    Please let me know if there possibility to potential error on customer condition.

    Or, is there possibility to failure IC?

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Genius 10385 points

    Satoshi-san,

    That is highly unusual. Do you observe this across multiple ICs?

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    Guru 19645 points

    Hi Ricardo

    I confirmed to customer, the other one bq25886 board occur the same result (unusual).

    By the way, customer board can not replace IC because of back side thermal Pad.

    If there any other points of notice, please advice me.

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Genius 10385 points

    Satoshi-san,

    I will try to recreate this in the lab tomorrow, but if I cannot recreate it I have no further advice. Let me know exactly what condition you would like me to recreate.

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    Guru 19645 points

    Hi Ricardo

    Thank you for trying,

    Our hope is recreate ICHGSET ×40% (normally 20 %) on COLD temp condition by the same customer condition, and become clear the reason of 40%.

    I modified customer condition, please see below, 

    ・ILIM and ICHGSET: 1.5A, VSET_setting: 8.2V, D+ and D-: Short

    ・Customer schematic is attached (sorry for only rough picture), please see below;

       I pickup different point by EVM default without battery side and switching FET.

    　⇒L2: 10μH, C2: 0.01μF, C6: 10μF, C10: 0.01μF, C12: 22μF, C13: 10nF, add D3, R8: 10Ω, VSET: 8.2V (JP16),

    　　RICHGSET and RILIM is adjust by switching FET(base is1.5A)

    　　(Designator is based on EVM)

    ・The reason for add switching FET is able to flexible change ICHGSET and ILIM value. 

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Genius 10385 points

    Satoshi-san,

    Unfortunately I was not able to recreate this issue.

    All findings are with VBUS: 5.5V; VBAT: 7.6V; ICHGSET set to 1.54A; VSET set to 8.2V

    Case one: ILIM is set to 1.5A MOSFET is OFF

    ICHG: 974.20 mA; REGN:5.0544V; TS: 2.5V, JEITA: Normal -> ICHG:297.78 mA; REGN:5.0493V; TS: 3.5V; JEITA: COOL

    Result: 297.78mA/1.54A = 19.33%

    Case two: ILIM is set to 2.85A, MOSFET is ON

    ICHG: 1.53896 A; REGN: 5.0594V; TS: 2.5V, JEITA: Normal -> ICHG: 298.10 mA; REGN: 5.0493V; TS: 3.5V; JEITA: COOL

    Result: 298.10mA/1.54A = 19.36%

    Best Regards,

    Ricardo