ChipCap® 2 Humidity and Temperature Sensor
14
Application Guide
3.2.2
PDM Output Pads (1.PDM_T, 2.PDM_H)
Temperature PDM (Pulse Density Modulation) appears on the PDM_T/Alarm_Low pad (1) and corrected Humidity
PDM appears on the PDM_H pad (2).
When pad (1) is selected for Temperature PDM, the Alarm_Low function is disabled and only one Alarm function
(Alarm_High: pad 8) is usable.
Note:
The ChipCap 2
PDM output is pre-programmed in the factory for Humidity and Temperature output mode.
3.2.3
Alarm Pads (8.Alarm_High, 1.Alarm_Low [optional])
As ChipCap 2 PDM is factory set for Humidity and Temperature output mode, only the High Alarm output can be used
in combination with ChipCap 2 PDM.
If both high and low alarm functions are required, pads 1 and 8 will be programmed at factory to use as Alarm_Low
and Alarm_High respectively with required high and low humidity values. In such a case, ChipCap 2 will output the
corrected humidity PDM only, See Section 7 for the alarm function.
3.2.4
Serial Clock & Data Pads (3.SDA, 4.SCL)
For
ChipCap 2 PDM output, both SDA and SCL pads are not used and must be connected to VDD.
3.2.5
Typical Circuit Connection
VDD and Ground are decoupled by a 220nF capacitor. V
core
(Not Used) and Ground are also decoupled by a 100nF
capacitor. SCL and SDL (not used) are connected to VDD.
Between ChipCap 2 and MCU (µC), Low Pass Filtering (see Section 6.2 on “Low Pass Filtering” on page 32 for more
information) with 10 k
Ω
resistors and 6,400 nF capacitors is added to create an analog signal.
Figure 9: Typical Application Circuit (PDM)
uC
(master)
6400nF
6400nF
2.3V < VDD < 5.5 V
SCL
VDD
CC2 A
V
CORE
GND
VDD
ALARM_HIGH
R
R
SDA
PDM_H
PDM_T
100nF
220nF
