Even the actual series like SHT1x and SHT2x belong to a top in this segment. Forthcoming series SHT3x (SHT30, SHT31 and soon also SHT35) addresses mainly those of you, requiring maximum accuracy even in limit values (humidity below 10% and above 90%), miniature dimensions and ultra low power consumption. So a main difference of a new SHT31 compared to SHT21 is, that a typical +-2% is maintained in a whole range. Together with a precise temperature measurement in element we still have a possibility to simply compute a dew point, what´s one of the key parameters for ventilation control (HVAC, heat recovery). If it´s “only” necessary to guide a humidity not to exceed certain level, then you´ll probably also use the output „Alert“ pin, able to start interrupt in a host MCU for instance or directly control further devices. Output of the SHT3x sensor is the linearized value, which can be easily transformed to a final value (%RH, °C).
SHT31 is available in 2 versions – SHT31-DIS-B with a digital output via well-proven I2C bus (2 selectable addresses) and also in a version SHT31-ARP-B with a linearized analogue (proportional) output. That´s why SHT31-ARP-B is an interesting alternative for direct processing in analogue circuits, as it contains 2 independent outputs with output voltage of 10-90% Vdd, responding to 0-100%RH and -45 to +130°C temperature. Digital output version also features wide possibilities of setting regarding measurement frequency, communication speed and other parameters.
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