• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 30 subscribers
  • Views 318 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

CC8531 VBAT monitoring

Pjotr
Prodigy 30 points


Hi,

I am trying to set up VBAT monitoring on the HP evaluation kit. However the CS8531 data sheet doesn't give any clues how to dimension the series resistor between VBAT and the battery. In the PP Wireless Configurator this resistor defaults to 100 Kohm, but on the board is a 47 Kohm resistor mounted. When setting to this 47 Kohm value in the PPWC it states an unusable range for the Li polymer battery.

Can any one point me to where to find more detailed information to dimension this VBAT resistor and what about the ranges given in PPWC? To what do I set the resistor value?

Regards

  • 0
    TI__Expert 3240 points

    Hi,

    The 47 kOhm resistor is a remnant from an old design.
    To be able to use the battery monitoring functionality on the HP evaluation kit, with the 3.7 V battery, the series resistor must unfortunately be replaced with resistor in the range 82-100 kOhm.

    Use the PPW configurator to see which measurable max and min voltage levels that are supported by a specific resistor value. Looking at the measurable voltage range in the PPW configurator the underlined values, in the example below, states the ensured measurable range for all the different CC85xx devices. 

    Lowest measurable voltage is in the range X.XX to X.XX V
    Highest measurable voltage is in the range X.XX to X.XX V

    Best regards,
    Johan 

  • 0 in reply to Johan Gustafsson
    Prodigy 30 points

    Thanks Johan,

    It clarifies the value of 47K. Hooked up a bench supply to figure out by trial and error and 47K definitely didn't work. Replaced it with a 100K resistor and that works fine. Actual values are 50mV - 100 mV off the set values as set in PPW configurator, but that is ok.

    For regular use battery monitoring is mandatory to switch off at lo-battery. Most build in protectors of Li-ion packs switch off for ever at too deep discharge. Did not tested it is the case with the supplied packs but I gues it is..

    Best regards,

    Peter