Are there any features that a customer is looking for that are not currently addressed, for single cell LiCoO2 chargers?
To get an idea of what parts already exist, one can go to ti.com and search on "bq240" or "bq241" and should get many charger designs.
Low Cost! What happened to the small, cheap 8-pin single cell LiIon charger chips that used to be available? I need them for all kinds of high volume cheap consumer products using small batteries. These products have no requirements for fast charging, extra protection, or anthing else other than charging at low current to 4.2VDC.
There are many circuits added for safety: Timers, precharge, battery temp sense, ovp etc.
TI recommends following the battery manufacturer's safety guidelines. If your company has decided to take on more risk by foregoing the safety feature, then an LDO with an input resistor will do the job. The resistor will limit the current to a maximum value and the curent will taper when the LDO hits voltage regulation.
Even with our fast charges, there are many features that can be disabled if the customer does not care to use them.
Not sure what you are calling expensive chargers....for >1M the prices drop to less than 50 cents (probably lower but I do not do pricing)....see bq24085.
How about more switching battery chargers for Li-Ion. Most people using batteries are interested in saving on heat and would like the smallest AC adapter for charging as possible. It would also be nice to have a charger that works better with the BQ27541 fuel gauge since it does not support SBS commands.