After the VBUS_GD bit is set and REGN LDO is powered, the device runs input source detection through D+/D– lines. The BQ25601D follows the USB Battery Charging Specification 1.2 (BC1.2) to detect input source (SDP/ DCP) and non-standard adapter through USB D+/D– lines.

After input source type detection is completed, an INT pulse is asserted to the host. in addition, the following registers and pin are changed:

1. Input Current Limit (IINDPM) register is changed to set current limit
2. PG_STAT bit is set
3. VBUS_STAT bit is updated to indicate USB or other input source

The host can over-write IINDPM register to change the input current limit if needed. The charger input current is always limited by the IINDPM register.