HI ,I have a question about 3 level convert.I have read about BQ25910 spec.
Before the 3 level convert start to work ,if D<0.5,the Voltage on Cfly is 0; Who charge it to VIN/2?
I know during the first stage,the VIN charge the Cfly to VIN/2.
Here is the question,how did the charge work？
why charge to VIN/2?
How to control charge?
who control the charge?
Why charge stop when the Cfly charged to VIN/2? Why Vsw is VIN/2?
Hi User5873469,
The Internal current source just use for pre-condition(before converter switching).
Cfly can be charged during the status of normal working below:
Hi Hi User5873469,,
As I mentioned before, bq25910 can adjust the duty cycle of Cfly charge status(state 1) and the duty cycle of Cfly discharge(State 3) to balance Vcfly.
Alen
Please click "This resolved my issue" button if this post answers your question
HI Alen：
I know the time of state 1 is as much as state 3.。state 1 charge，state 3 discharge .I just understand how it charge CFly which voltage is 0 after stage3,than charge to Vin/2 in stage1.
During and after stage 3 the voltage on Cfly is still Vin/2.
Cfly dischanrge in stage 3,why the voltage still Vin/2? Should it be dropped?
From this picture, Voltage on Cfly didnt change , charge and dicharge, the Voltage on Cfly is still the same.
WHY?Is the power take from Cfly too small to change the Vcfly during stage 3?
