Power supply circuit for constant current source

Abstract

The invention discloses a power supply circuit for a constant current source. The power supply circuit comprises a main control chip, a direct voltage outputting module and a constant current outputting module, wherein the main control chip is connected with the direct voltage outputting module and the constant current outputting module respectively to be used for outputting a control instruction according to power supply voltage needed by a load circuit so as to regulate the output voltage of the direct voltage outputting module; the direct voltage outputting module is used for supplying a variable direct voltage for the load circuit; the constant current outputting module is used for outputting a constant electric current to the load circuit. The power supply circuit disclosed by the invention can reduce the calorific value and enlarge the scope of the output current.

Description

technical field [0001] The invention relates to the field of power supply control, in particular to a constant current source power supply circuit. Background technique [0002] A constant current source is a power supply capable of supplying a constant current to a load. The constant current source allows the load resistance to vary widely while the load current remains constant. Constant current sources are generally divided into transistor constant current sources, field effect transistor constant current sources, and integrated op amp constant current sources. The power field effect tube can output a large current and has better output characteristics: when the voltage between the source and the gate of the power field effect tube is constant, the current of its drain is constant and within a certain range The voltage change between the drain and the source has nothing to do with the drain current, and has better constant current performance. In large-capacity battery...

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Problems solved by technology

[0003] However, the power supply voltage of the traditional constant current source is generally a fixed voltage, which not only limits the maximum output current, but also is not suitable for applications where the load resistance changes greatly and the output current range is large.

Because in the occasions where the output current is large and the load resistance changes greatly, the voltage between the drain and source of the power field effect transistor changes greatly, resulting in large tube consumption.

The heat generated due to the large tube consumption will increase the junction temperature. If proper heat dissipation measures are not taken, it will cause a large temperature drift, thereby deteriorating the constant current performance, and even burning the power FET

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