ZSSC3122 Datasheet, PDF (56/64 Pages) List of Unclassifed Manufacturers – Low Voltage Capacitive Sensor Signal Conditioner

ZSSC3122 Datasheet
7.3 Bang-Bang Control System
In this example, the only outputs are the alarm pins. They
are programmed to control a high voltage bang-bang hu-
midity control system. External devices are not needed
if not using high voltage.
Vsupply +1.8V to 5.5V
If the humidity gets too high, the ZSSC3122 activates the
dehumidifier using the Alarm_High pin. If the humidity
gets too low, it activates the humidifier with the
Alarm_Low pin. The alarm registers must be set to
appropriate trip and hysteresis points (See section 3.8).
The configuration settings are shown in Table 7.3.
The output selection bits should either be set to I²C™ or
SPI since depending on the PDM configuration, both
alarms are not supported. Additionally, I²C™ and SPI
are lower power than PDM. This application does not
use I²C™ or SPI, so Update Mode must be used
because Sleep Mode commands cannot be sent. The
fastest update rate is used for this example. External
devices are needed to control the outputs because a
voltage source greater than VDD is used.
0.1µF
0.1µF
GND
cLite ™
VDD ^ZSSC3122
Vcore
VSS
Alarm_High
C0
Alarm_Low
CC
12V
12V
Dehumidifier
GND
Humidifier
GND
Figure 7.3 Bang-Bang Control System Example
The alarm pins control NMOS devices so the alarm pins must be full push-pull and output high when the alarm is
on, so the polarity bits are set to 0 and the open drain bits are set to 0.
In this example application, a faster response time may be needed, so the AFE configuration settings show 10-bit
resolution for both capacitance and internal temperature. C_Config settings have been selected for a capacitance
range of 5.8pF to 7.2pF (see Table 2.1).
Table 7.3 Example 3: Configuration Settings
Configuration Register
ZMDI_Config (Table 5.2)
Cust_Config (Table 5.5)
C_Config (Table 5.3)
T_Config (Table 5.4)
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0^†
0
0
0
1 0 1 1 0 00XX00 0
0^†
0^†
0
0
0 0 0000101000
0^†
0
0
0
0
1 0^† 0^† 0^† 0^† 1 0 0 0 0 1
1^†
0^†
0^†
0^†
0
1 0^† 1* 1* 0* 0* 1* 0* 0* 1* 0*
* The factory settings are set for a full span temperature range from -20°C to +125°C. Do not change this setting unless a different temperature range is needed.
† Reserved setting – do not change factory settings.
© 2016 Integrated Device Technology, Inc.
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January 25, 2016