Hi,
I'm designing for bq25896 and trying to understand if/how to properly use the ICO feature.
The finished product is a handheld instrument with a LiIon cell. I anticipate that it will be charged from a variety of USB power sources. One of them will be an AC/DC USB C connector charger sold with the instrument (so correctly reporting maximum current (3.0 A)). Another will be a USB type A to USB C cable with an integrated resistor that correctly reports maximum current (500 mA). In addition to these officially supported power sources, it can be expected that the user will take whatever USB cable with a USB C connector he/she has for charging/powering the instrument. In this case I assume that either maximum current isn't reported at all or the reported value is found to be incorrect.
(AFAIK, with a USB C connector the downstream-facing device (charger or PC) reports maximum current by standardized resistor divider values (500 mA, 1.5 A, or 3.0 A).)
I have read the bq25896 datasheet and also browsed the ICO AN (SLVA812C Extracting Maximum Power from an Adapter with Input Current Optimization Feature) and would like to run my conclusions by you; Is the ICO feature mostly useful when used with an AC/DC charger? I mean, a PC USB port is probably powered from a more powerful 5 V rail so we might blow a PC USB port fuse or overheat the PC 'rail' before it droops so much that the ICO detects it?
In other words: in the scenario I describe above, should the use of ICO be reduced to a second-line protection in case the reported maximum current is incorrect? Rather than a first-line detection mechanism to detect maximum current?
Best regards
Niclas