提出一种完全通过数字方式实现恒流的控制电路, 省去了传统恒流控制电路中的误差放大器、锯齿波产生器和PWM比较器。本文采用数字电路, 将副边反馈电压与内部基准电压相比较, 得到一个方波, 并以此为依据来控制功率管的占空比和周期, 从而达到恒流控制的目的。基于0.5 μm BCD工艺, 在25℃, TT工艺角下对电路进行仿真, 结果表明这种控制电路可以实现高的功率因数(PF>0.9)和精确恒流输出(误差<6%), 具有很高的可靠性和工程实用性。

A digital constant current control circuit was presented, eliminating the error amplifier, PWM comparator and sawtooth generator devices in the traditional constant current controller. The digital circuit got a square wave by comparing the feedback voltage from the secondary and the internal reference voltage, and the duty cycle and frequency of the power NOSFET based on it was modulated, so as to achieve a constant current control. Based on 0.5μm BCD process, at , it is shown bythe circuit simulation that the control circuit can be achieved with high power factor (PF> 0.9) and precision constant current output (error <6%) and a very high reliability and practicability at 25 ℃ with TT process.