• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 2 answers
  • Subscribers 62 subscribers
  • Views 298 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.

BQ24073: BAT PIN1,2 are in floating when battery is removed

Muthu Pattan
Prodigy 10 points
Part Number: BQ24073
Other Parts Discussed in Thread: BQ25180

We are using BQ24073RGTT battery charger. In this pin no 2,3 (BAT1, BAT2) we have connected 10uF capacitor, a battery connector and we connected to the processor through the resistive divider to detect the battery detection or a dead battery detection. In this case, even though after removing the battery also we are receiving a floating data on the processor from the BAT1, BAT2 pins through the resistive divider. But we are expecting a LOW signal to be present since the battery is not connected but we are receiving floating data. Please help us on this.

  • 0
    TI__Mastermind 23220 points

    Hi Muthu,

    When the device has no battery, it will operate in battery detection mode as shown in this figure from the datasheet. It will not provide a low signal as it has this routine to know when to consider a new charge cycle and when a battery is removed. This allows a differentiation between dead battery and a missing battery. 

    You'll need to account for this behavior

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Prodigy 10 points

    Thanks for the reply. But the Detection can be written as

    1) If my battery is removed VBAT will be solid LOW. So, battery is not connected. (But here it is a square wave, how can FW person write a code for this detection?)

    2) If it is a dead or repair battery, how this chip can support for the detection? How is it differentiating a Dead battery or No battery? 

  • 0 in reply to Muthu Pattan
    TI__Mastermind 23220 points

    Hi Muthu,

    Can you provide a waveform of what you are seeing at the battery pin when the battery is removed? Or can you describe it in more detail other than LOW?

    Muthu Pattan said:
    In this case, even though after removing the battery also we are receiving a floating data on the processor from the BAT1, BAT2 pins through the resistive divider. But we are expecting a LOW signal to be present since the battery is not connected but we are receiving floating data.
    Muthu Pattan said:
    If my battery is removed VBAT will be solid LOW

    I'm a little confused cause it sounds like you initially saw some voltage but now you are claiming it is low? Can you share a measured voltage? A waveform would be preferred.

    Muthu Pattan said:
    If it is a dead or repair battery, how this chip can support for the detection? How is it differentiating a Dead battery or No battery? 

    This is described in the datasheet. A dead battery would provide a voltage with no significant changes to voltage while a missing battery will see the capacitor changing voltage because of the detection current. 

    Let me know if there are any questions. 

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Prodigy 10 points

    If my battery is removed as per our schematic BAT1, BAT2 should be LOW or HIGH. So that my FW engineer will write a code stating that, whenever my BAT1, BAT2 pin reaches LOW, print that "Battery is removed". This is our requirement.

    But unfortunately, here it is a square wave, how can FW person write a code for this detection using a square wave as a detection signal? It should be any High or LOW state change to detect the battery is removed. 

    Please suggest a coding technique to write for this battery removal detection or please schedule a Teams meeting with us to discuss more about this. 

  • 0 in reply to Muthu Pattan
    TI__Mastermind 23220 points

    Hi Muthu,

    Thanks for the clarification!

    What I've recommended in the past is to monitor the battery pin as it is, using a filtering function in software to be able essentially monitor the battery voltage which you are most likely already doing. You will need to do a comparison within the frequency of the battery detection routine to see frequent change in BAT pin voltage. Then, when you compare, you should see battery pin low, then battery pin high. It is a very quick battery low, then battery high that happens frequently that should distinguish a missing battery as opposed to a dead battery.

    I've seen this done with a timer interrupt running every so often that detects a falling edge on the battery pin. If within a few period of the battery of the battery detection routine, there is a few falling edges, then the battery is missing. 

    You can look at this BQ25180 thread for some other inspiration: (+) BQ25180: How to detect battery disconnection? - Power management forum - Power management - TI E2E support forums

    Best Regards,

    Anthony Pham