EVAL-AD7156EBZ Analog Devices Inc, EVAL-AD7156EBZ Datasheet - Page 7

• Manufacturer Part Number: EVAL-AD7156EBZ
• Description: Evaluation Board I.c.
• Manufacturer: Analog Devices Inc

Specifications of EVAL-AD7156EBZ

• Sensor Type: Touch, Capacitive
• Interface: I²C
• Voltage - Supply: 1.8 V ~ 3.6 V
• Embedded: No
• Utilized Ic / Part: AD7156
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Sensitivity: -
• Sensing Range: -
• Lead Free Status / Rohs Status: Supplier Unconfirmed

Threshold Modes
The upper Threshold box allows you to set the AD7156
threshold to either adaptive or to fixed see Figure 17.
When the upper mode box is set to adaptive mode, the lower
Threshold box allows you to define the threshold level to be
positive, negative, in-window, or out-window see Figure 17.
Adaptive Mode
In adaptive mode, the thresholds are dynamically adjusted,
ensuring indication of fast changes (for example, an object
moving close to a capacitive proximity sensor) and eliminating
slow changes in the input (sensor) capacitance, usually caused
by environment changes such as humidity or temperature.
Fixed Mode
In fixed mode, the threshold is fixed to a defined value, and
changes in the input capacitance are indicated when the input
data crosses the fixed threshold.
INPUT CAPACITANCE
Negative Threshold
The negative threshold is set below the average, used when a
negative change on the capacitive input is expected. The change
on the input is indicated when the input data goes below the
threshold.
Figure 11. Adaptive Threshold Indicates Fast Changes and Eliminates Slow
INPUT CAPACITANCE
Figure 13. Negative Threshold Mode Indicates Negative Change in Input
CAPACITANCE
THRESHOLD
THRESHOLD
THRESHOLD
NEGATIVE
OUTPUT
OUTPUT
INPUT
OUTPUT
Figure 12. AD7156 in Fixed Mode
Changes in Input Capacitance
FAST CHANGE
OUTPUT ACTIVE
FAST CHANGE
Capacitance
OUTPUT ACTIVE
NEGATIVE CHANGE
OUTPUT ACTIVE
SLOW CHANGE
SLOW CHANGE
TIME
TIME
TIME
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Positive Threshold
The positive threshold is set above the average, used when a
positive change on the capacitive input is expected. The change
on the input is indicated when the input data goes above the
threshold.
In-Window Threshold
The in-window threshold has two thresholds, one above and
one below the average. The output stays high as long as the
input data stays inside threshold window. A change on the input
is indicated by a low on the output when the input data goes
either above the positive threshold or below the negative
threshold.
Out-Window Threshold
The out-window threshold has two thresholds, one above and
one below the average. A change on the input is indicated when
the input data goes either above the positive threshold or below
the negative threshold.
INPUT CAPACITANCE
INPUT CAPACITANCE
Figure 14. Positive Threshold Mode Indicates Positive Change in Input
CAPACITANCE
THRESHOLD
THRESHOLD
THRESHOLD
THRESHOLD
THRESHOLD
POSITIVE
OUTPUT
NEGATIVE
NEGATIVE
POSITIVE
Figure 16. Out-Window (Adaptive) Threshold Mode
POSITIVE
OUTPUT
Figure 15. In-Window (Adaptive) Threshold Mode
INPUT
OUTPUT
Figure 17. Threshold Mode Select Options
OUTPUT ACTIVE
INPUT OUTSIDE THRESHOLD WINDOW
Capacitance
OUTPUT ACTIVE
INPUT INSIDE THRESHOLD WINDOW
OUTPUT ACTIVE
POSITIVE CHANGE
EVAL-AD7156
TIME
TIME
TIME