Thermostat Design For HVAC Control System

HVAC is more and more popular now and there is a definite trend in the HVAC industry toward smarter,more energy-efficient and compatible products.This brings more challenge to thermostat design.This is the design for thermostat used in North American.It is a universal(heat pump or conventional)thermostat platform used to control 24 VAC & RS485 residential systems compatible with electric or gas heat with or without air-conditioning.It has two selected programmable mode,can save energy with making sure the room's comfort.It use the two communication circuit: 24 VAC and RS485,monitoring the whole system to make the HVAC in the optimal working environment,to save energy and more smart.This design use high performance Freescale KL36 micro,based on ARM Cortex M0+.The thermostat have a customized segment LCD,displays the current temperature as sensed by the internal temperature sensor.And include 6 low profile positive tactile response buttons with a dedicated backlight button.DC-DC step bulk regulator LM2594 and,constant current led driver,high precision temperature and humidity sensing is the big features of the design.Low noise latching rely drive circuit and the real-time accurate CA comfort alert circuit make the system running safe and reliably.The design can pass all the tests,including ESD,EFT,IEEE and meet all the specifications of the design.