Tiny Thermostat

I need a tiny thermostat, something that will close a circuit or ground a line when things get hot, like 50C. It has to fit in like 3x3mm of space. There are lots of temperature sensor chips,like the LM26, which are wonderful and small, but it has to be able to run on and switch 9V. The LM26 only goes up to 5.5 volts. And unfortunately we don't have the room to add 5V step down regulators or level shifters. There are sensors that tolerate 9V, but they are in much larger packages.

Any ideas? Thanks in advance!