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Original question:

BQ25606: Standalone Charger schematics review

BQ25606: RT1 and RT2 value for 100K NTC

Naveen Kumar S1
Prodigy 250 points
Part Number: BQ25606

Hi, 

We have used BQ25606 for a standalone charger application.

Looks like the charger is going to suspend state and hence we are seeing LED blinking which is driven by STAT pin.

Attaching a video showing the STAT LED behavior. Please note that we are driving two LEDs using STAT pin. The LED behaviour is same with and without battery. 

  • Red LED is driven by PG pin
  • BLUE LED driven by STAT is to indicate Charging status
  • GREEN LED again driven by STAT is to indicate Charge Full status

We are seeing that BLUE LED is also glowing along with Green blink. Is this expected behaviour during suspend state? Please clarify.

The thermistor value of the battery being used in 100K NTC. The calculations of the resistor divider for the TS pin provided in datasheet is based on 10K NTC.

We need help to tune the RT1 and RT2 values for 100K NTC for our battery thermistor.

Appreciate your quickest response.

Thanks,

Naveen

  • 0
    TI__Mastermind 40635 points

    Hello Naveen,

    The RT1 and RT2 are definitely different for 100k NTC than 10k NTC. The process is as follows:

    1. Select your T1 and T5 temperature thresholds.

    2. Use thermistor datasheet to calculate thermistor resistance at T1 and T5 temperature threshold.

    3. Use Equation 1 and Equation 2 in Section 9.3.5.4 to calculate RT2 and RT1.

    Regards,

    Mike Emanuel