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BQ25628: BQ25628: Custom design: ADC enabled but TS_ADC stuck

Chamith Koperahewa
Prodigy 50 points
Part Number: BQ25628

Tool/software:

Hello, 

I have a product that uses BQ25628 as a battery charger IC, the device was made while referencing the BQ25628 EVM. Everything works fine but at times, TS_ADC stops responding and only reports the same value even when the temperature is changed. During this period all the other ADC values are fully responsive and even TDIE_ADC too varies with respect to the external temperature. 

The following are the configurations of the related registers

  • TS_IGNORE = 0b (used)
  • ADC_Control Register
    • ADC_EN: 1b (enabled , not default, resetted by watchdog too)
    • ADC_RATE: 0b (Continuous, default)
    • ADC_SAMPLE: 11b (9bit, deafult)
    • ADC_AVG: 1b (Running average)
    • ADC_AVG_INIT: 0b (default,  start avg usingthe existing reg value
  • TS_ADC_DIS: 0b enable (default)
  • WATCHDOG: Disabled(00b)

Restarting the battery charger IC can help reset this issue. This causes the battery charger IC to not respond to temperature changes and doesnt update TS_STAT.

Any feedback on this matter would be appreciated. 

Thank you

  • 0
    TI__Mastermind 31270 points

    Hello Chamith, 

    Thank you for reaching out via E2E. Please see my comments below. 

    Firstly, can you share your hardware setup (i.e. schematic) for TS pin connections so I can review? 

    Secondly, let me clarify that TS_STAT status register will work independent of whether TS_ADC channel is enabled or disabled. You mention TS_STAT does not change in response to temperature changes is the NTC you are using for battery temperature monitoring subjected to the temperature change in your testing? It will likely be shown in the schematic I have requested, but what NTC are you using in your design? 

    Best Regards,

    Garrett

  • 0 in reply to Garrett Kreger
    Prodigy 50 points

    Hello Garett, 

    Thank you for your response. 

    I have attached a picture of the particular section.

    Notes on the schematic

    • BAT_TS is connected directly to the battery NTC. which is: 10K - 3435K

    According to section 8.3.5.4 in the datasheet (pasted below), it states that the IC will follow charging profile based on the feedback from the TS pin, doesn't that mean that the IC will use the TS value as an input to determine the charging profile? 

    Thank you again

  • 0 in reply to Chamith Koperahewa
    TI__Mastermind 31270 points

    Hello Chamith, 

    Thank you for your response. Unfortunately it appears there was an issue with attaching the picture of the TS portion of your schematic as I am unable view the image. Can you please help to resend the schematic image at your earliest convenience? 

    Chamith Koperahewa said:
    According to section 8.3.5.4 in the datasheet (pasted below), it states that the IC will follow charging profile based on the feedback from the TS pin, doesn't that mean that the IC will use the TS value as an input to determine the charging profile? 

    Based on feedback from TS pin the BQ25628 will make adjustments to charging parameters shown in Figure 8-3. If TS is beyond TS_HOT or TS_COLD charge will be suspended. If TS is beyond TS_COOL charge current will be reduced by default and if TS is beyond TS_WARM threshold full charge voltage level (VREG) will be reduced. 

    Best Regards,

    Garrett