请高手指点,TL494BUCK电路出现的问题

低负载的时候输出正常,高负载的时候输出大幅振荡,如图.电容严重发烫.
输入15V,输出0-12V可调,电压在12V时电流最大到10A.
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原理图:
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SCH:
2354671246370411.rar