LM393 Dual Voltage Comparators

The LM393 is a pretty common chip made by TI, STM, ONSemi (And probably others too).  This one is from 2006 and the package was branded with STMicro logo yet unusually (For a big semi company) the silicon die has no ST markings.

The die is just 0.76mm x 0.72mm (Or 0.75mm square give or take the odd 10μm 🙂 ) Removing the gold bond wires after the decap on such a small die was really tricky.

From the ST datasheet this is the schematic (of one half of the circuit)

And from another datasheet this is the pin out (GND=Vcc)

Spending a few minutes looking at the die photo and the schematic, I can see there is a bit more going on than the schematic indicates. For instance each of the inputs go to a transistor base (Which they do) of a transistor whose collector is connected to GND/Vcc on the schematic (Which it isn’t directly) and the emitter on the schematic is connected to a transistor base and diode (I can see the diode connections, but can’t really identify the transistor base connection.)

Its an interesting little die that I think is still being produced today.

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