Help identifying circuit function

[bitman]

I have a dead Raspberry Pi 3 B 1.2 that I'm trying to revive. It died with some magic smoke as it got overloaded driving a LED matrix. The attached image can be found as part of the total schematics here: https://www.raspberrypi.org/documentation/hardware/raspberrypi/schematics/rpi_SCH_3b_1p2_reduced.pdf.

From my probing, it looks like DMMT5401 isn't healthy so I will replace it (E1->B1 is shorted). But before I do that, I initially thought this was a current mirror but I'm no longer sure of that because the two bases aren't connected.  In particular R2 and R3 confuses me and what having different values would achieve. The current mirrors I've found all are B1->B2 and no resistors on the Collector side.  So what is it that I'm looking at if it's not a current mirror?

[gcewing]

The bases are actually connected, but I don't think it's a current mirror.

The whole thing is designed to act like a diode with zero forward voltage drop, to prevent backward flow of 5V power. If it is powered from the right, R2 turns on the right transistor, which connects the gate of the mosfet to its source and keeps it turned off. When it is powered from the left, the left transistor conducts and raises the base voltage of the right transistor, turning it off. R3 then pulls the gate of the mosfet to ground, turning it on.

[perieanuo]

Hi,
Without spice modeling, I think is just a power switch with some little retard function and kinda slow-start function.surely not current mirror.
On the other hand, why 1% precision resistors ...I really disagree.


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