Datasheet

HDC1080

SNAS672A –NOVEMBER 2015–REVISED JANUARY 2016

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Typical Application (continued)

9.2.2 Detailed Design Procedure

When a circuit board layout is created from the schematic shown in Figure 15 a small circuit board is possible.

The accuracy of a RH and temperature measurement depends on the sensor accuracy and the setup of the

sensing system. The HDC1080 samples relative humidity and temperature in its immediate environment, it is

therefore important that the local conditions at the sensor match the monitored environment. Use one or more

openings in the physical cover of the thermostat to obtain a good airflow even in static conditions. Refer to the

layout below ( Figure 18) for a PCB layout which minimizes the thermal mass of the PCB in the region of the

HDC1080, which can improve measurement response time and accuracy.

9.2.3 Application Curve

The data shown below was acquired with the HDC1080EVM. A humidity chamber was used to control the

environment.

Figure 16. RH vs. Time

9.3 Implementation and Usage Recommendations

9.3.1 Soldering

When soldering the HDC1080 use the standard soldering profile IPC/JEDEC J-STD-020 with peak temperatures

of 260 °C.

When soldering the HDC1080 it is mandatory to use no-clean solder paste and no board wash should be

applied. The HDC1080 should be limited to a single IR reflow and no rework is recommended.

9.3.2 Chemical Exposure and Sensor Protection

The humidity sensor is not a standard IC and therefore should not be exposed to particulates or volatile

chemicals such as solvents or other organic compounds. If any type of protective coating must be applied to the

circuit board, the sensor must be protected during the coating process.

9.3.3 High Temperature and Humidity Exposure

Long exposure outside the recommended operating conditions may temporarily offset the RH output. Table 10

shows the RH offset values that can be expected for exposure to 85 °C and 85 % RH for durations between 12

and 500 hours (continuous).

Product Folder Links: HDC1080