A digital load adaptive variable voltage constant current source circuit

Abstract

The invention discloses a digital load adaptive variable voltage constant-current source circuit, and belongs to the technical field of electronic devices. The main structure of the circuit comprisesa single-chip microcomputer (1), a digital to analog conversion module (2), a power output module (3), a load judging module (4), a delay compensation module (5), a voltage tracking module (6) and a power failure protection module (7). The circuit can actively adapt to the change of the load during work, and has the advantages of high efficiency, wide load adaptation range, high safety and high reliability.

Description

technical field [0001] The invention belongs to the technical field of electronic equipment. In particular, it relates to a digital load adaptive variable voltage constant current source circuit. Background technique [0002] Constant current sources have important applications in many fields such as LED drive, laser drive, sensor drive, and various glow discharge light source drives. The basic principle of the constant current source circuit is generally to use the nonlinear characteristics of the triode or FET and the deep negative feedback technology to make the output current controlled by the control voltage, and keep the current flowing through the load constant when the load changes. In the constant current source circuit, the stability of the current and the efficiency of the circuit are two crucial parameters. [0003] The existing technology closest to the present invention is the Chinese patent "A digital program-controlled constant current source" (application ...

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Problems solved by technology

However, like other prior art constant current source circuits, this patent has the problem of poor load adaptability

Specifically, a constant current source circuit can only drive a fixed load, or only allow the load to change within a small range. When the load increases, the triode that controls the current will enter the saturation region, resulting in a rapid increase in the maximum output current. drop (that is, it cannot continue to maintain a controlled output constant current), and when the load decreases, the triode will enter the undervoltage region (because the load is small, the voltage generated across the load is also small, which is called undervoltage in this field ), since the triode and the load are in the same series circuit, and the triode is a nonlinear device, the reduction of the load voltage will cause the triode to automatically bear the excess voltage of the circuit, which will lead to a sharp increase in the internal power consumption of the triode, while the internal power consumption of the triode It is a "by-product" of the circuit, which is harmful to the system: on the one hand, the increase in power consumption of the tube will increase the temperature of the tube sharply and increase the risk of tube burnout (reducing the service life of the instrument); on the other hand, when the load The inability to adjust the power supply in time during the change causes the efficiency of the entire circuit to be greatly reduced, which is very unfavorable when using a constant current source for mobile devices

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