The moment the PMOS switch is turned on, the inrush current is too large and the PMOS burns out...

[vbsemi]

说到MOS管烧坏，通常是因为它在SOA工作空间中不工作，也有MOS管过流的情况。

例如，该电路中PMOS晶体管的最大允许电流为50A，而MOS晶体管导通时最大电流达到80+，则电流非常大。

此时，PMOS 被过度指定，我们可以在 SOA 曲线上看到它不在 SOA 范围内工作，这将导致 PMOS 损坏。

那么，如果您选择更高电流的PMOS呢？当然可以，但成本会更高。

我们可以选择调整外围电阻或电容，使PMOS导通更慢，从而降低电流。

例如，在调整R1、R2和gs之间的跳线电容时，当Cgs调整到1uF时，Ids的最大值仅为40A，就电流而言是可以的，符合80%的降额。

（50 安培 * 0.8 = 40 安培）。

接下来，我们来看一下功率，从SOA曲线来看，MOS管的开启时间约为1ms，此时最大功率为280W。

芯片的正常热阻为122°F/W，最高结温可达302°F。

假设环境温度为 77°F，那么 1ms 可以承受的瞬时功率约为 357W。

这里PMOS的实际功率是280W，没有超过限制，这意味着它在SOA领域正常工作。

因此，当MOS晶体管在转动时电流冲击较大时，可以适当调整Cgs电容，使PMOS在SOA区域工作，可以避免MOS损坏的问题。

 

[FvM]

I approved the post because circuit and simulation waveforms are partly self-explanatory. Please notice that English posts are required at Edaboard, can you add at a translation of problem description?

A simulation schematic with load specification is unfortunately missing. Obviously it's the load that kills the switch respectively a lack of current control.

--- Updated Monday at 7:29 AM ---

Look at transistor datasheet SOA (safe operation area) spec. Might be that the transistor is simply too small to handle the load.

 

[dick_freebird]

The turnon event will put a lot of pulsed thermal power
onto the switch device and the heat sinking has to have
enough close-in thermal mass to keep juntion temperature
peak, sane. Far-away thermal mass won't be fast enough
to save the junction at the top of the stack.

But too, turnon has to be leisurely enough that the switch is
in control of the current (despite that it also has to take the
abuse meanwhile). Experiment with gate slew control and
load dV/dt feedback to force a ramp that leads to a tolerable
max current during charging. Take a stab at modeling the
thermal stack, with masses and time constants, realistically
all the way to the D-B, drain-neck junction so that you can
estimate a safe pulsed operating area and "make it so".