Called 2525020210002, it works over 0 – 100% relative humidity, typically to within ±1.8%RH (±3.5%RHmax) over 20 – 80%.
Also in the device is a -40 to +125°C temperature sensor, accurate to ±0.2°C across 0 to 60°C, and ±0.6°C over its full range.
Regardless of the actual error, the sensor can be operated at one of three repeatability levels: high (±0.08%RH ±0.04°C), medium (±0.15% ±0.07°C) or low (±0.25% ±0.1°C).
The supply can vary across 1.08 and 3.6V, drawing 2.2uA, 1.2uA or 0.4uA respectively depending on repeatability mode. These are average figures at one reading per second. During reading, the figure is typically 320uA (500uA max), and there is a 50uA idle mode plus an 80nA shut-down.
On-board heater
For situations when the sensor surface is covered in condensed water, an on-board heater can be activated at various power levels for a choice of durations. The maximum is 200mW for 1s.
When mounting the device, leaving gaps in copper planes around it will reduce the effects of heat traveling through the PCB, possibly at the expense of noise performance.
The company warns that the “humidity sensor is not a normal electronic component” and “the sensing element is made of polymer. Long-term exposure
above normal humidity (20 to 60%RH) and temperature (10 and 50°C) range may offset the sensor value”.
The cure is baking at between 100 and 110°C at 5%RH for 24 hours, and then re-hydrating at 20 to 30°C at 80%RH for 48 hours.
A development board to AdaFruit’s FeatherWing standard is available.
Its data sheet is a fairly trivial affair, and it is to the ‘user manual’ you must to turn for most of the 2525020210002 specification. There is also a document (ANM006) comparing this device to the earlier 2 x 2mm 2525020210001.