The RE46C803 is a low voltage low power CMOS carbon monoxide detector companion IC. The RE46C803 provides all of the analog, interface, and power regulation functions for a microcontroller-based CO or toxic gas detector.? The RE46C803 is intended for use in standalone 3V battery applications. It features a boost converter and horn driver circuit suitable for driving a piezoelectric horn, an LED driver, a 3.3V ?regulator for microcontroller voltage regulation, a 1.8V regulator for the CO op amp supply, and a