Hi,
In our application we use two sources for VBUS rail: main with 2A charge current limit, or auxiliary low current with 0.8A charge current limit. Both power sources can be connected and disconnected at any time, and charger is supposed to operate autonomously. We would like to have the possibility to limit charge current, when auxiliary power source is in use. To do that, we plan use circuit with two parallel resistors like this:
When USB_VBUS (2A capable) voltage is not present, Q6 is turned off, so resistance seen from ILIM pin is equal to about 660R. When USB_VBUS is connected, then Q6 gets opened and resistance seen from ILIM pin drops to about 265R which gives us charge current limit equal to 2A.
Is this approach correct?
