The RE46C800 is a low power CMOS carbon monoxide detector companion IC. The RE46C800 provides all of the analog, interface, and power management functions for a microcontroller based CO or toxic gas detector. It is intended for use in both 3V and 9V battery or battery-backed applications. It features a high performance operational amplifier, a 3.3V regulator for microcontroller voltage regulation, a boost converter, horn driver circuit suitable for driving a piezoelectric horn, an LED driver, and an I/O circuit for communication with interconnected units.