SLUS821J October 2008 – May 2017
In order to provide an output voltage on SYS, the bq2423x require either a power supply between 4.35 V and 6.0 V input for bq24230 and between 4.35V and 10V for bq24232 to fully charge a battery. The supply must have at least 100 mA current rating connected to IN; or, a single-cell Li-Ion battery with voltage around 2.2 V connected to BAT. The source current rating needs to be at least 1.5 A in order to provide maximum output current to SYS.
In order for charging to occur the source voltage measured at the IN terminals of the IC, factoring in cable/trace losses from the source, must be greater than the VINDPM threshold (in USB mode), but less than the maximum values shown above. The current rating of the source must be higher than the load requirements for OUT in the application. For charging at a desired charge current of ICHRG, IIN > (ISYS+ ICHRG). The charger limits IIN to the current limit setting of EN1/EN2.
Some low-cost adapters implement a half rectifier topology, which causes the adapter output voltage to fall below the battery voltage during part of the cycle. To enable operation with low-cost adapters under those conditions, the bq2423x family keeps the charger on for at least 20 ms (typical) after the input power puts the part in sleep mode. This feature enables use of external low-cost adapters using 50-Hz networks.