基于TL494控制的同步整流BUCK恒流源的设计

为了解决线性恒流源功耗大,输出电流小的缺点,提出了一种基于TL494控制的同步整流BUCK开关恒流源。该恒流源采用PWM控制原理调节主开关管和同步整流管的占空比来实现输出电流从0到20A稳定连续可调。控制器采样输出电压,当输出电压超过预定的10V电压时,主开关管关断,输出电压稳到10V,实现过压保护。另外,给出了电路原理图并进行了样机的制作与测试。测试结果表明,其恒流精度相对误差最大值为0.75%,因此该方案是可行的。

Design of Constant Current Source of BUCK Converter Based on Synchronous Rectification Control of TL494

For the drawbacks of large power consumption and small output current of linear constant current source, a constant current source of BUCK converter based on synchronous rectification control of TL494 is proposed. It can be adjusted from 0 to 20A stability, adjustably and continuously. The duty cycle D of main switch and synchronous rectifier is regulated by PWM control principle to achieve a stable output current. Sampling output voltage, when output voltage exceeds a predetermined voltage of 10V, the switches is shutdown, output voltage is stabilized to 10V to achieve over-voltage protection. The design of the schematic is presented, and prototype is made, test results show that its current precision relative error maximum is 0.75%, so the program is feasible.