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. 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.

LM393 Die Photo

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.)

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

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