一种用于原边电流采样的自适应前沿消隐电路

An Adaptive Leading Edge Blanking Circuit Applied in Primary Current Sampling

提出了一种用于原边反馈反激变换器的自适应前沿消隐电路。根据不同的原边峰值电流产生自适应的前沿消隐时间信号,使消隐时间可以跟随原边峰值电流变化。一方面,该自适应前沿消隐电路能使原边电流信息采样更准确,避免开关管导通时的高频尖峰引起误采样。另一方面,产生的自适应前沿消隐时间可以减小电流采样电路的轻载静态功耗。仿真结果表明,前沿消隐时间误差最小低至1.5%,在不同工艺角下最大误差为5%左右。

An adaptive leading edge blanking circuit applied in primary-side regulation flyback converter was proposed. An adaptive leading edge blanking time signal was generated by this circuit according to different primary peak current value, making the blanking time follow the primary peak current’s variation. On the one hand, the primary side current information could be sampled more accurately by the proposed adaptive leading edge blanking circuit, avoiding mis-sampling caused by the high frequency spikes when the switch turned on. On the other hand, the static power of the current sampling circuit could be reduced by the adaptive leading edge blanking time at light load. Simulation results indicated that the minimum leading edge blanking time error could be limited to 1.5%, and the maximum error was about 5% at different corners.