您好，以下是应用场景：6-28V输入，正常12V输入，输出12V，30A，-40-85℃，400KHz开关频率应用，目前遇到的瓶颈是：
1.不知道IC的功耗如何计算，IC的发热源主要是MOS栅极栅极驱动吗，是否有其他的比较大的热源，目前这个应用场景IC大概温升多少呢；
2.外置MOS的Qg是否有要求，目前选型为43nC的，不知是否满足要求；
3.用TI官方的LM5176计算工具，将上述参数输入后，在6V输入的时候电流在12-20A效率会迅速下降，20A后又会上升（如下图），目前不知道出现这个问题是为什么；
请帮忙解答一下，谢谢！
The main losses in the IC will be the gate driver losses and the losses of the VCC regulator.
You can calculate the driver losses with the following formula:
For calculating the VCC regulator losses you can use I_gate x4 (I_gate=P_gate/V_gate).
Also you can use the power stage designer, it has a driver losses calculator (https://www.ti.com/tool/de-de/POWERSTAGE-DESIGNER )
Then you could back calculate the the temperature of the IC by using the thermal resistances given in the datasheet.
However, the IC temperature will also depend on the temperature of the PCB, which will also be heated by the external components like MOSFETS and Inductor.
So the calculation is only a rough estimation. In the end it should be checked in the lab to be sure.
