Hi all,
I am using the LMP8646 to limit the current that is used to charge a 5F capacitor to 4V. I utilized the online webench design tool to determine the component values, and I set my current limit to 20mA. I have a bench power supply powering a voltage regulator that is set to 4V, and this output runs to the LMP8646 system and the capacitor.
When I enable the power supply, the measured current to the capacitor starts off high (around 350mA) and settles at around 100mA once the voltage of the capacitor gets to around 2.4V. At around 3.1V the current drops to 82mA and stays at this value until the capacitor is done charging.
My first question is: why does it take so long for the current limiting to kick in?
My second question is: I must have miscalculated when determining component values, as I want the current limit to be 20mA instead of 82 - 100mA. To lower the current limit, I believe I need to change the value of Rout. If this is correct, would I want a lower or higher Rout value?
Thanks very much,
Paul
