• State
  • Locked Locked
  • Replies 2 replies
  • Subscribers 64 subscribers
  • Views 399 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

bq24272 External NTC Monitoring datasheet clarification

Hans Christian Glittenberg
Expert 2235 points
Other Parts Discussed in Thread: BQ24160

Hi,

there is obviously an error in formula (2) for Vcold and Vhot. Both constants cannot be 0.60. Please advise which constants to use.

Also, the datasheet does not specify what temperatures to use for Rhot and Rcold. According to figure 6, there are no comparators for detecting the in-between temperature ranges specified in figure 5. However, the register associated with the NTC describes four temperature detection thresholds: T_HOT > T_WARM > T_COOL > T_COLD

So, I will assume there are more comparatores available, and that Rhot corresponds to Thot = 60 C, and Rcold to Tcold = 0 C. Please clarify and confirm.

Regards

HC

  • 0
    Expert 2235 points

    A followup: The user guide for the evaluation module states that the resistors calculated for the TS is for a 10k thermistor. R_HI = 1870 Ohm and R_LO = 4120 Ohm. Using the equations in the datasheet and manipulating, with V_HOT = V_DRV * 0,3 (which is used for some other TI parts - see above post), R_COLD = 8788 Ohm and R_HOT = 994 Ohm. These values do not correspond to a typical 10k thermistor, but rather a 3k thermistor! see link http://www.amwei.com/news.asp?news_id=79

    Please advice!

    Regards

    HC

  • 0 in reply to Hans Christian Glittenberg
    TI__Guru**** 155286 points

    The 272 is uses JEITA.  The datasheet needs to be updated.  Please refer to the bq24160 datasheet in the meantime.

    The EVM resistor values are for use with the onboard potentiometer and not intended to represent actual values in a real system.  Please use the equations to compute the values for your thermistor.