BQ25713B: 发热比较严重

输入电压15.5V，IIC没有接的情况下VSYS输出9V。

VSYS端带载电流500mA左右，芯片发热比较严重，没有接铅酸电池充电的情况下，只是在VSYS端接了负载，附件是图纸。帮忙看看图纸有没有问题。

BQ25713B.pdf

Star Xu：

您好，请确认THERMAL pad是否接地。

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小维：

有接地，八个过孔，过孔孔径0.4。

温度最高到80°

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Star Xu：

您好，请参考下面的内容

 As this is a charge controller, the thermal dissipation/heat will be localized on the external power stage, i.e your external switching FETs and inductor. The key top optimizing thermal performance is making sure you have enough vias to ground plane for effective heat dissipation, and clean uninterrupted ground plane. With regards to choice of external components, you want to minimize 

conduction loss

Choose lower DCR inductor and lower RDSon FET

switching/gate drive loss

choose switching FET with lower Qg

Some other layout suggestions:

You can improve heatsinking by adding a thicker layer of a GND copper pour
Increase the copper area of the high power traces
Reduce the effects of radiated heat by further separating the MOSFETs and inductor from each other

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小维：

这个发热的温度，是否有规定一个范围呢？

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Star Xu：

您好，关于热参数请参考数据手册8.4 Thermal Information