一种新型低成本过流保护阈值调整电路设计

Design of a New Low-Cost Over-Current Protection Threshold Adjustment Circuit

针对输入纹波因数较大的LED驱动电路,提出了一种新型的过流保护阈值调整电路。该电路应用于峰值电流检测模式的反激式LED驱动电路,可适应不同输入电压下过流点偏差。使用新型结构,电路可自动调节过流保护电路阈值,而无需采样输入电压大小,过流阈值调节范围为0.78-0.88V。电路结构简洁,有效预防了功率管因过流而可能造成的损坏,同时获得更高的电源效率。该电路适用于大多数输入电压纹波较大的AC-DC电源芯片。

Based on LED driver circuit with large input ripple factor,a new type of adjustable over current protection circuit is presented.The circuit is used in the peak current detection mode flyback LED driver,and can be adapted to the deviation of over current point under different input voltages.With this new structure,the circuit can automatically adjust the threshold value of the over current protection circuit,without the need for sampling the value of the input voltage.It simplifies the structure of the system and effectively prevents the power MOS which may cause over current damage,while gains higher power efficiency.The circuit structure is simple,and the overcurrent threshold adjustment range is from 0.78V -0.88V.The chip is universal for most of the AC-DC power chip with large ripple factor.