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My project is MP6602 No Power to Motor while No Fault Condition - #4 by tmi11er passing NO current and it is far from anything like the recommendations for heat dissipation.
Proposition: The chip trips its current limit very very early in proportion to the die temperature.
Dialectical: Nowhere in the datasheet do they write the mathematical relationship between the die temperature and the current limit.
Conclusion: There is a large amount of work necessary in calculating a suitable mounting for the MP6022 to operate properly and not enough information to know it will operate without experimentation unless you have the necessary experience in the same circumstances.