• State
  • Locked Locked
  • Replies 2 replies
  • Subscribers 62 subscribers
  • Views 583 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.

BQ76930: About Charging Discharging Path and Current

Jake Jung
Expert 1915 points
Part Number: BQ76930
Other Parts Discussed in Thread: BQ78350

Hi. I am being tested with BQ 76930EVM.

I intend to apply BQ76930 with 7S1P batteries to my system. (BQ76930 only, not BQ78350)

I have few questions.

1. Power Supply is connected Pack+ ,- for charging. 

Charging is normal when "CHG" and "DSG" are ON, but not charging when only "CHG" is ON(DSG is off).

Is this normal operation?

2. If the PACK +,- of BQ76930 is connected to load, connect charge source to the PACK+,- to charge, will charge and discharge operate at the same time?

3. If the load has a discharge current of 1A and a 2A DC Adapter is connected at PACK+-, what is the charge / discharge operation and current?

Please let me know.

Thanks.

  • 0
    TI__Guru 54715 points
    Hi SS,
    The typical FET connection for bq76930 like the EVM has serial FETs and a single set of PACK terminals. Current flow in or out of the battery will depend on the system voltages and any current switching or direction between the charger, load and battery needed by the system would be handled separately from the battery protection.
    1. With only CHG on (and DSG off) the battery may still charge due to the body diode of the DSG FET. However if the battery and the charger are at the same voltage the body diode will not be biased on no charge current will flow, the battery would only charge to a diode drop below the charger.
    2. Yes, if both a charger and load are connected to the PACK terminals, current will flow in or out of the battery depending on the voltage difference.
    3. It depends on the voltages under load. If the battery voltage is low and is charging at 2A, then 1A is drawn by a load, only 1A remains to charge the battery. If the battery is almost fully charged with current approximately 0A and the adapter voltage does not drop when the load is applied, the adapter may provide 1A to the load and the battery may remain at approximately 0A. If the battery is almost charged and the adapter voltage does drop with the 1A load, the battery may provide some load current and the adapter may provide the remainder of the 1A needed.
  • 0 in reply to WM5295
    Expert 1915 points
    Thanks a lot WM5295