Patent ID: 9167853
Filing Date: 2015-10-27
Classification: A24F,H02J

Abstract:
1. A USB charger for electronic cigarettes, comprising a USB interface configured for connecting with a power supply and a load end configured for connecting with a load, wherein, the USB charger for electronic cigarettes further comprises a voltage comparison unit, a benchmark circuit, a sampling circuit, a current detecting element, a state indicating unit, and a low voltage difference linear regulator connected between the USB interface and the load end; the benchmark circuit is connected between an output end of the low voltage difference linear regulator and an input end of the voltage comparison unit; and the state indicating unit is connected with an output end of the voltage comparison unit; wherein, the state indicating unit comprises a first light emitting diode and a second light emitting diode, the voltage comparison unit comprises a first voltage comparator and a second voltage comparator, the first light emitting diode and the second light emitting diode are respectively connected with an output end of the first voltage comparator and an output end of the second voltage comparator; wherein, the sampling circuit generates a comparison voltage at a positive input end of the first voltage comparator and a negative input end of the second voltage comparator respectively, and the benchmark circuit transmits a benchmark voltage to a negative input end of the first voltage comparator and a positive input end of the second voltage comparator respectively; wherein, the current detecting element is a detecting resistor, and the detecting resistor is connected between a cathode of the load end and ground; the benchmark circuit comprises a first resistor and a second resistor, and the sampling circuit comprises a third resistor; wherein, the first resistor and the second resistor are connected in series and then are connected between a fifth pin of the low voltage difference linear regulator and ground, and the negative input end of the first voltage comparator and the positive input end of the second voltage comparator are connected between the first resistor and the second resistor respectively; one end of the third resistor is connected between the detecting resistor and the cathode of the load end, and the other end of the third resistor is connected with the positive input end of the first voltage comparator and the negative input end of the second voltage comparator respectively; wherein, a cathode of the first light emitting diode is connected with the output end of the first voltage comparator, an anode of the first light emitting diode is connected with an anode of the load end, a cathode of the second light emitting diode is connected with the output end of the second voltage comparator, and an anode of the second light emitting diode is connected with the anode of the load end; wherein, the low voltage difference linear regulator receives power via the USB interface and charges the load, and is further configured to provide over-current protection, short-circuit protection, and over-temperature protection in real time in the charging process; the current detecting element is configured for detecting the charging current, and forms a voltage thereon; the sampling circuit is configured for acquiring a node voltage between the load end and the current detecting element, and generates the comparison voltage at the input end of the comparison unit according to the node voltage; the benchmark circuit is configured to generate the benchmark voltage, and transmits the benchmark voltage to the voltage comparison unit; the voltage comparison unit is configured to compare the comparison voltage with the benchmark voltage, determine a charging state of the USB charger for electronic cigarettes, and control the state indicating unit to indicate the charging state according to the charging state.