AD7151BRMZ Analog Devices Inc, AD7151BRMZ Datasheet - Page 12

• Manufacturer Part Number: AD7151BRMZ
• Description: IC CAP CONV 1CH ULT LP 10MSOP
• Manufacturer: Analog Devices Inc
• Type: Capacitance-to-Digital Converterr

Specifications of AD7151BRMZ

• Input Type: Voltage
• Output Type: Digital
• Interface: 2-Wire Serial
• Current - Supply: 120µA
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Resolution (bits): 12bit
• Sampling Rate: 100SPS
• Input Channel Type: Single Ended
• Data Interface: 2-Wire, I2C, Serial
• Supply Voltage Range - Analog: 2.7V To 3.6V
• Supply Current: 70µA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AD7151
SENSITIVITY
In adaptive threshold mode, the output comparator threshold is
set as a defined distance (sensitivity) above the data average,
below the data average, or both, depending on the selected
threshold mode of operation (see Figure 29). The sensitivity
value is programmable in the range 0 to 255 LSBs of the 12-bit
CDC converter (see the Register Descriptions section).
HYSTERESIS
In adaptive threshold mode, the comparator features hysteresis.
The hysteresis is fixed to one-fourth of the threshold sensitivity
and can be programmed on or off. The comparator does not
have hysteresis in the fixed threshold mode.
TIMEOUT
In the case of a large, long change in the capacitive input, when
the data average adapting to a new condition may take too long,
a timeout can be set.
The timeout becomes active (counting) when the CDC data
goes outside the band of data average ± sensitivity. When the
timeout elapses (a defined number of CDC conversions is
counted), the data average (and thus the threshold) is forced to
follow the new CDC data value immediately (see Figure 31).
DATA AVERAGE
DATA AVERAGE
THRESHOLD
THRESHOLD
THRESHOLD
NEGATIVE
POSITIVE
POSITIVE
OUTPUT
DATA
Figure 29. Threshold Sensitivity
Figure 30. Threshold Hysteresis
OUTPUT ACTIVE
DATA
OUTPUT ACTIVE
TIME
TIME
SENSITIVITY
SENSITIVITY
HYSTERSIS
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The timeout can be set independently for approaching (for change
in data toward the threshold) and for receding (for change in data
away from the threshold). See Figure 32, Figure 33, and the
Register Descriptions section.
INPUT CAPACITANCE
CAPACITANCE
THRESHOLD
DATA AVERAGE
DATA AVERAGE
DATA AVERAGE
+ SENSITIVITY
– SENSITIVITY
OUTPUT
LARGE CHANGE
Figure 31. Threshold Timeout After a Large Change in CDC Data
THRESHOLD
Figure 32. Approaching Timeout in Negative Threshold Mode
INPUT
OUTPUT ACTIVE
DATA AVERAGE
Figure 33. Positive Timeout in Negative Threshold Mode
OUTPUT
Shortens Period of Missing Output Trigger
Shortens False Output Trigger
TIMEOUT RECEDING
TIMEOUT APPROACHING
TIMEOUT
LARGE CHANGE IN DATA
OUTPUT ACTIVE
TIME
TIME
TIME