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BQ25606: Wide tolerance on REGN makes it difficult to reliably sense presence of battery by thermistor voltage

Part Number: BQ25606

We planned to sense insertion of a battery into the charger by reading the voltage derived from TS. However the data sheet shows the limits on REGN to be 5.6 to 6.65V and battery presence must be sensed at temperature down to  0°C. The combination results in limit values for not present and for present at low temperature to overlap.   To simplify the solution it would be helpful to know whether the actual distribution of devices in your production (for ~ 1 mA load and with 12V input ) is much tighter than the published range, and will not change significantly on future production. 

For example; If 99.5% of units will fall within 6.0 +/-  0.2V and that will remain correct for years to come, that would avoid our having to develop a different type of solution.

Thank you,

Lon

  • Lon:

    Understood you want to use TS voltage to detect battery presence. What is your purpose to detect battery presence? I am thinking if there is other ways to detect battery presence. Thanks for your suggestion. Our REGN specs in the datasheet are based on 6 sigma of distribution. If you use 3 sigma, the voltage will be +/-0.25V. That means around 93% of units will fall into the +/-0.25V tolerance.
  • Mao,

    Thank you for replying. The application is a charger into which the battery is inserted when charge is needed. This is a common application for a charger. I appreciate your clear answer about the distribution on REGN. In our application a +/- 0.25V spread still results in marginal separation between battery present at high REGN and low temperature versus no battery at low REGN. We will have to pursue a solution in FW.
  • Lon:

    Thanks for letting us know. We will consider higher accuracy on REGN in future products.