• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 63 subscribers
  • Views 342 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.

BQ24640 charge current regulation

Bartholin Emeric
Prodigy 30 points
Other Parts Discussed in Thread: BQ24640

Hello,

I use a BQ24640 for charge a supercapacitor (25F) with the following setting:

Icharge=120mA  => Viset = 0.82V

Vc= 2.6V.

Vin = 15V

During  the design, I measure two different charge current :

Icharge =  90mA when Vc < 1.6V  

Icharge = 120mA when Vc>1.6V 

I not find any explanation of this comportment in the datasheet.

Are you any explain for this? (Current limitation? ...)

Best regards

Emeric

  • 0
    Intellectual 265 points
    Probably because it was in the Precharge zone. What value does your Sense resistor has?

    I dont have much knowledge with super capacitors but I assume that you are making a relative big leap by going from 1.6V to 2.6.
    This regulation is because thats how you want to charge a battery but I dont know about super caps

    If this the problem, theres an appnote that can suppress the precharge zone and that the charge current always will be (40mV/Rsense) and not (4mA/Rsense)

    Kindly