Application Guide
35
ChipCap® 2 Humidity and Temperature Sensor
7.5 Alarm Polarity
For both alarm pins, the polarity of the alarm output is selected using the Alarm Polarity bit in the Alarm_High_Cfg
and Alarm_Low_Cfg registers in EEPROM word Cust_Config (see Table 16 on page 38 for bit assignments). Another
feature of the polarity bits is the ability to create two high alarms or two low alarms. For example, with applications
requiring two high alarms, flip the polarity bit of the Alarm_Low pin, and it will act as a high alarm.
However, in this case, the effect of the alarm low registers is also changed: the Alarm_Low_On register would act like
the Alarm_High_Off register and the Alarm_Low_Off register would act like the Alarm_High_On register. The same
can be done to achieve two low alarms: the Alarm_High pin would have the polarity bit flipped, and the two
Alarm_High registers would have opposite meanings.
Figure 21: Bang-Bang Humidity Control (High Voltage Application):
ChipCap 2 PDM: 1 Alarm/Humidity Output (Optional)
VDD
VDD
2.3V < VDD < 5.5V
ALARM_HIGH
GND
uC
(master)
SCL
V
CORE
GND
6400nF
6400nF
SDA
100nF
220nF
(10k
:
(10k
:
DEHUMIDIFIER
CC2 A
(slave)
PDM_H
PDM_T
