The HDC3120EVM integrates two TLV9030 comparators which provide analog alert functionality. When the analog temperature or humidity outputs of the HDC3120 exceed a user-defined threshold (set using a potentiometer), the respective comparator swings high towards the positive supply rail. Two 10kΩ potentiometers (R6 and R7) are provided to set the comparator thresholds. Adjust the potentiometers using either a flathead or PHILLIPS® screwdriver.

To set up the HDC3120EVM comparator functionality of the HDC3120EVM, observe the following tips:

• Use a multimeter to measure the resistance across the potentiometers terminals before tuning (RH_POT and GND for RH_ALERT | T_POT and GND for T_ALERT).
• Each potentiometer includes 11 indexed markings. An arrow on the yellow adjustment screw indicates the current position of the wiper.
• Turning the screw clockwise increases the resistance (sets higher threshold), while turning counter-clockwise decreases the resistance(sets lower threshold).

Figure 2-7 illustrates a close-up of the potentiometer and Figure 2-8 illustrates the location of each test point. Table 2-1 is provided as reference for the potentiometer values based off the position of the arrow.

Figure 2-7 Potentiometer Close-up

Figure 2-8 Potentiometer Multimeter Test Points

Figure 2-9 HDC3120EVM Comparator and Potentiometer Interface Points