Down now to the heart of the brain (Just ponder that metaphor for a moment. Done? Wonderful, let’s move on). A quick look at the noteworthy integrated circuits running the Nest Protect:

Freescale SCK60DN512VLL10 custom Kinetis K60 low-power 100 MHz MCU

Silicon Labs EM357 Ember Zigbee SoC

Freescale SCKL16Z128V custom Kinetis KL1x general purpose MCU

Texas Instruments LM324A quadruple op-amp

Murata Type ZX 2.4 GHz Wi-Fi 802.11b/g/n module (with Broadcom BCM43362 chipset)

Texas Instruments TPS62737 Step-Down Buck Converter