I am designing a charger which takes input power from computer USB port and fast charge for 3 NiMH cells(1.2V each, 300mAh) connected in series. I noted that somebody suggested BQ2002 in this forum earlier, so I studied the user guide: http://www.ti.com/lit/ug/sluu007b/sluu007b.pdf
However I do not understand the function of the LM317. How does it controls the constant charging current and voltage to the cells?
Also during the charging period, the USB needs to supply power to the device MCU as well. I planned to add a diode at the output pin of the charging IC to form an ORing diode supply, is it fine?
Can you suggest a solution?
Thank you.