Making a burglar alarm
The TMP006 is a PIR, but a temperature sensor. This should be used in a situation where the temperature to be measured is equal over the full viewing angle. That would require the burglar to be very close to the sensor, something he might not want to. LDRs are no use either, they detect light levels.

The common way to detect a person's presence is a PIR presence/motion detector. I've used the Panasonic NaPiOn for this, which at the time was the smallest existing PIR.   



It has a matrix of detection zones, which, combined with the multi-faceted lens will detect even slight movements at meters distance.  

Use is easy. It has three pins: ground, Vcc, and output. The output goes high if the sensor detects a person moving in its detection field.

Further reading:
NaPiOn design manual