Constant current step-down power supply

Abstract

The invention provides a constant-current step-down power supply which comprises a first input port, a second input port and a load. The constant-current step-down power supply also comprises a constant-current step-down device, a terminal voltage-stabilizing tube, a positive half-cycle charging circuit and a negative half-cycle charging circuit. One end of the positive half-cycle charging circuit is connected with the low-voltage end of the constant-current step-down device, and the other end of the positive half-cycle charging circuit is connected with the negative electrode of the terminal voltage-stabilizing tube. The positive electrode of the terminal voltage-stabilizing tube is connected with the second input port and the lower end of the load. One end of the negative half-cycle charging circuit is connected with the low-voltage end of the constant-current step-down device, and the other end of the negative half-cycle charging circuit is connected with the negative electrode of the terminal voltage-stabilizing tube. In the positive half cycle of an alternating current power supply, the alternating current power supply charges the positive half-cycle charging circuit. In the negative half cycle of the alternating current power supply, the alternating current power supply charges the negative half-cycle charging circuit. The maximum output current, which is supplied to the load, of the constant-current step-down power supply can be greater than the input current so that the power supply can be applied to circuits with a larger output current, and is especially suitable for all-weather working occasions of low input power, such as an electric energy meter and the like.

Description

technical field

[0001] The invention relates to a power supply, in particular to a constant current step-down power supply. Background technique

[0002] Low-power power supplies generally use switching power supplies and transformer power supplies. However, switching power supplies have problems such as electromagnetic interference, high cost, and poor overload capacity; transformer power supplies also have problems such as high cost, large size, and heavy weight. Due to the advantages of low cost, simple circuit, no interference, and high reliability, the constant current step-down power supply is widely used in low-power power supply circuits. After the power supply voltage and frequency are determined, the current provided by the power supply is determined by the resistance or capacity of the resistor or capacitor, and the maximum output current can only provide a current value close to the input current; but in practical applications, due to the connection problem of th...

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