• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 64 subscribers
  • Views 154 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.

BQ24278

golan kormian
Intellectual 880 points
Other Parts Discussed in Thread: BQ24278

hi,

questions regarding  BQ24278: 

  1. When AC adapter is connected (lets say 5V) what is the voltage at SYS/SW pin (out pin connect to the load)?
  2. Which voltage is recommended to supply for high efficiency and minimum heat dissipation?
  3. What are the consequences if I connect load directly to the battery? this load will operate only at backup, when AC adapter is not connected.
  4. when AC adapter connect the total current consumption is about 1.6A (not include battery charging) at 3.3V (i use buck-boost switcher to reduce voltage). one of the feature is GPRS module(GE910). its average current consumption is 220mA, but has 2A current picks. can this influence on the  output supply both when adapter is connect or battery discharge?
  • 0
    TI__Guru**** 153546 points

    1.  Could be between 3.4V-4.37V depending on several factors including VBAT voltage level, input current loop active, VINDPM loop active, battery not installed or charging diabled.  See page 3 of datasheet.

    2.  Lower voltages result in higher conversion efficiency and therefore lower heat dissipation in the IC.

    3.  If this only happens when AC adapter is not connected, then no consequences.  Consequence when AC adapter is connected is battery may never completely charge/not terminate charge.

    4.  The charger will prioritize current to the SYS output as needed.  If more current is needed than SYS can supply, then the charger enters supplement mode and will supplement current from the battery.  Depending on the conditions per 1, the SYS voltage could change during the transient.