LM2678T-ADJ output voltage of 5V

LM2678T-ADJ output voltage of 5V.When the input voltage is 12V, the effect of output voltage 5V is very good, and the effect of 5A over-current protection is very good.When the input voltage is 24V,  some loaded LM2678T-ADJ chip can not stable output pressure, and the effect of 5A over-current protection is bad.When the output is over-current , the voltage of 5V jump high , then burn LM2678T-ADJ.Please give some guidance advice.

Note: the input voltage range for 10V – 29V. Layout and wiring of peripheral circuit reference PDF specification.The output inductor of peaking coils is configured to 22 uh.Output capacitance of SMD electrolytic capacitors of SANYO is configured to 220 uf.

Neil Li：

如果高压输出有异常，可以贴一下SW的波形

Luke Pan：

Hi,

What's  the inductor saturation currrent level? Can you offer the board layout?

rui luo：

回复 Luke Pan:

inductor saturation currrent level is 5A.THANK YOU

rui luo：

回复 Neil Li:

就是接负载瞬间电压会升高，形成尖脉冲，时间维持在MS级，然后恢复正常。

Neil Li：

回复 rui luo:

需要调试下环路。

Luke Pan：

回复 rui luo:

LM2678的current limiting最大可达8.75A，所以电感饱和电流一定需要大于这个值的，否者即使IC能及时减小占空比，但是电感饱和了，还是没有办法对电流起到限制作用。

rui luo：

回复 Luke Pan:

电感换为10A的也没有效果

rui luo：

回复 Neil Li:

能否详细说明下！