Abstract: A interface circuit includes: a power supply circuit, configured to output a DC voltage; a voltage conversion circuit, configured to convert the DC voltage to a target voltage, wherein the voltage conversion circuit is a step-down conversion circuit; a first Type-C port and a second Type-C port, configured to be connected to the respective loads; a switch circuit, connected to the power supply circuit, the voltage conversion circuit, the first Type-C port and the second Type-C port respectively; and a USB controller, configured to communicate with the first Type-C port and the second Type-C port respectively, and regulate the DC voltage and the target voltage according to supply voltages of the loads connected to the first Type-C port and the second Type-C port, and control the switch circuit to apply the DC voltage or the target voltage to a Type-C port connected to a corresponding load.

Abstract: A circuit for sampling current includes a current transformer, a reset resistor, a diode, a sampling switch, and a current sampling resistor. The current transformer includes a primary winding and a secondary winding. The reset resistor and two ends of the secondary winding are connected in parallel. The sampling switch, the diode, and the current sampling resistor are connected in series and then connected to two ends of the reset resistor in parallel. The primary winding is for connecting to a circuit to be sampled. When a current flows through the primary winding and the circuit to be sampled and the sampling switch is turned on at a negative AC half cycle, the circuit for sampling current samples the current flowing through the circuit to be sampled.