STCC2540/5011/5021 USB Charging Controllers STMicroelectronics STCC2540/5011/5021 USB Charging Controllers integrate, in one package, a USB charger controller, a wide bandwidth data switch, and a high current power switch. The device emulates several profiles compatible with USB battery charging standard, BC1.2, Chinese telecommunications standard YD/T 1591-2009, and proprietary charger modes. The device asserts the charging flag in DCP modes if the charging current is higher than the threshold. In CDP mode, it asserts the charging flag after the CDP negotiation if the charging current is higher than the threshold. After the current drops below the threshold, the output is de-asserted, allowing the host to turn off the high-power DC-DC converter and reduce overall consumption in S4/S5 states, critical when the host is battery supplied.