Other Parts Discussed in Thread: BQ24640,
Hi, a design of the BQ24640 has been made to charge 8 supercapacitors of 70F to 22.6V, and then has been implemented on the BQ24640EVM evaluation board.
The design has been tested and indeed the supercapacitors are charged up to 22,6V. But once this voltage is reached, the supercapacitors start discharging due to the leakage current and it doesn’t start charging again.
To avoid this behavior and in order to keep the supercapacitors charged, a hysteresis control was implemented, so that when supercapacitors were charged to 22,5V the CE pin was forced to low, and when they self-discharged to 22.35V, the CE pin was forced to high; With the objective to have the supercapacitor voltage always in this range.
When this design was tested again, the supercapacitors charged up to 22.5V and the CE pin was forced to low, but when CE was forced back to high the charging did not restart. It was found that once CE is forced to low, even if it is returned to high, the only way to restart charging the supercapacitors is discharging those almost to 0V. It should be noted that all the conditions in section 7.3.4 of the data sheet were checked, and all conditions were met.
Is this behavior normal, i.e., that when CE is lowered, the charging is not restarted when forced to high?
