BQ24640: Charging ramp period

Roberto Franchelli

Part Number: BQ24640

I have a question regarding the ramp of charge. Above there is our schematic .
Is settable?
We are using the super cap 30F 5.4V .
If the super cap is between 1.5 to 2V I see a sort maintenance status where the current is very low ( 25mA ) . After that period,10 second, the charge is very fast . Is something that could be set ?

over 5 years ago

0 Kedar Manishankar over 5 years ago

TI__Mastermind 24075 points

Hi Roberto,

Are you referring to the soft start of BQ24640? This should be around 10ms not 10s. This part does not have a precharge current phase, so it will jump directly into constant current phase, where current is regulated according to charge current set by ISET. It is not configurable.

0 Roberto Franchelli over 5 years ago in reply to Kedar Manishankar

Prodigy 20 points

Thanks for reply.
I have this behaviour that I described only if the voltage of capacitor is from 1.5V to 2V . If the charge start form 0 V or after 2V I have not this behaviour. Could be due to the costrucition of capacitor?

0 Kedar Manishankar over 5 years ago in reply to Roberto Franchelli

TI__Mastermind 24075 points

Hi Roberto,

Can you take a waveform capture of charge current, SRN, VCC and PH during the period when you mention that charge current is low?

0 Kedar Manishankar over 5 years ago in reply to Kedar Manishankar

TI__Mastermind 24075 points

Hi Roberto,

We have not heard from you in a while and assume your issue has been resolved. If not feel free to ask more questions.

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BQ24640: Charging ramp period