www.austriamicrosystems.com/Capacitive-Sensors/AS1716 Revision 1.02 8 - 12
AS1716
Datasheet - Application Information
9 Application Information
Figure 13. Application Diagram, minimal requirements
Values of the suggested external components are indicative and need to be characterized for each specific application.
Typical Piezo Sensor:
Resistor from 500kΩ to 1MΩ
Capacity from 900nF to 1.5µF
Typical wire equivalent circuit:
Capacity to groung from 100pF to 400pF / meter
Capacity between wires strongly depends on type of wires (twisted-pair strongly suggested)
Resistance is typical 50mΩ / meter @ 20°C
Layout rules
Input Resistors and Capacitors at the inputs should be placed as close as possible to the stonger possible source of disturbances (i.e. the
input connector).
The input lines should be kept as short as possible and routed close to each other.
The filter capacitor (100nF) on supply should be a ceramic type and placed as close as possible to the chip.
VSSA and VDDA lines on PCB should have larger width than other signals to minimize resistance, especially if the 10µF capacitor is not
very close to the chip.
The output line should be kept as short as possible.
Due to
failure
up to 16V
560k
1200pF
typical
sensor
100pF
1k
100pF
1k
-
+
Multiple Feedback LP filter
fc ~23kHz typ.
Gain Control
x0.5, x1, x2, x4
INN
INP
GA
GB
100Ω
to
1k
OUT
10nF
µC
12 Bit AD
50k S/s
NC
VSSA
VDDA
100nF
10µF
V
4.5...5.5V
-
+
-
+
VDDA/2
-
+
VDDA/2
+
-
VDDA
VDDA/2
VDDA/2
VDDA/2
AS1716
