A Dual-loop Feedback Constant Current Source Circuit

Abstract

The invention discloses a dual-loop feedback constant-current source circuit and belongs to the technical field of electronic technology. The dual-loop feedback constant-current source circuit structurally comprises a current-limit setting module (2), a current setting module (3), a current output module (7) and a first feedback module (8). The circuit is characterized by also structurally comprising a reference voltage module (1), a subtractor module (4), a PID control module (5), an adder module (6) and a second feedback module (9). The above circuit is of a dual-loop negative feedback structure. Therefore, the output current of the circuit is high in stability and safety. The circuit can be widely applied in multiple occasions.

Description

technical field [0001] The present invention belongs to the technical field of electronic technology. It particularly relates to a high-stability double-loop feedback 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. In some specific application fields, the stability of the output current of the constant current source is very important. For example, in the laser driving application, a small current change will cause a large change in the output optical power and lasing wavelength, and these changes will directly endanger the device. safe use. Commonly used measures to improve current stability include: 1. Using the nonlinear magnetization principle of magnetic saturation reactor to improve stability; 2. Connecting a large resistance in series in the load circuit (relative to the load resistance); 3. ...

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Problems solved by technology

Among these schemes, the first scheme is greatly affected by the device itself and has limited improvement in stability; the second scheme can effectively reduce the impact of changes in load resistance due to a large resistor connected in series in the load circuit. The influence of the output current, but due to the existence of a large resistance in the load circuit, the output current is very small when the power supply voltage is constant, generally only in the milliampere level, and most of the voltage is dropped on the large resistance. The efficiency is extremely low; the third scheme is the most effective way to improve current stability because of the automatic adjustment function of the negative feedback network itself, which can automatically stabilize the output current without being affected by load changes. In the disclosed technology, a single linear feedback network is generally adopted. The disadvantages of this scheme are: first, once the feedback network fails, the system will be in an open-loop working state, and the output current will increase sharply, which is easy to damage the load and the circuit itself; secondly, the use occasions are limited, and can only be applied to occasions where the load responds linearly to the current. The constant current effect of the constant current source of the network will be greatly reduced

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