Emerson Electric Co.
POWER SUPPLIES FOR THERMOSTATS IN HVAC SYSTEMS

Abstract:

A power supply for a thermostat in an HVAC system includes a rectifier having a rectifier input for receiving input power from a voltage source, and a rectifier output. The thermostat also includes a rechargeable battery having a battery output, a voltage regulator coupled to receive a voltage from the rectifier output, and a boost regulator including a boost regulator input. The boost regulator is configured to convert a voltage received at the boost regulator input from the voltage regulator or the battery output. The thermostat also includes a battery charger management circuit configured to monitor a battery charge state of the rechargeable battery, and to selectively charge the rechargeable battery according to an operation state of the thermostat. Example methods of operating a power supply for a thermostat in an HVAC system are also disclosed.