I found two ICs that might be able to limit voltage and current. There are probably others.
I need to see if they can limit voltage to 2v7 and current to 240mA.
MAX17525
I don’t really understand what this does. It seems like it simply limits current, and not voltage, and the current limiter seems to high.
MAX14575
The MAX14575A/MAX14575AL/MAX14575B/MAX14575C programmable current-limit switches feature internal current limiting to prevent damage to host devices due to faulty load conditions. These current-limit switches feature a low 32mI (typ) on-resistance and operate from a +2.3V to +5.5V input voltage range. The current limit is adjustable from 250mA to 2.5A, making these devices ideal for charging a large load capacitor as well as for high-current load switching applications.
This too only limits current and not voltage. So it looks like I will have to use a regulator to get the voltage down to 2v7.
I see there are regulators called LDO (Low Dropout) the benefit of which I don’t understand.
But here’s a Texas Instruments regulator that will output 2v7 upto 300mA. Perhaps I need to be able to produce more than that to make sure the current limiter can generate enough? Anyway 300mA for now.
TLV70227QDBVRQ1 looks like this.
So basically, I’ll have the LDO sucking 5v5 and blowing 2v7 at 300mA into the current limiter which will pass through 2v7, but chop the current at 240mA (10C).
Now my question is, do I really need the current limiter, or can I rely on the LDO to limit the current, or does it catch fire if the supercap tries to draw too much?
