AD7143 Analog Devices, AD7143 Datasheet - Page 24

• Manufacturer Part Number: AD7143
• Description: Programmable Controller for Capacitance Touch Sensors
• Manufacturer: Analog Devices

Specifications of AD7143

• Resolution (bits): 16bit
• # Chan: 8
• Sample Rate: n/a
• Interface: I²C/Ser 2-Wire,Ser
• Analog Input Type: n/a
• Ain Range: ± 2 pF (Delta C)
• Adc Architecture: Sigma-Delta
• Pkg Type: CSP

AD7143
Table 12. Additional Information about Environmental Calibration and Adaptive Threshold Registers
Register
NEG_THRESHOLD_SENSITIVITY
NEG_PEAK_DETECT
POS_THRESHOLD_SENSITIVITY
POS_PEAK_DETECT
STAGE_OFFSET_LOW
STAGE_OFFSET_HIGH
STAGE_OFFSET_HIGH_CLAMP
STAGE_OFFSET_LOW_CLAMP
STAGE_SF_AMBIENT
STAGE_HIGH_THRESHOLD
STAGE_LOW_THRESHOLD
Bank 2
Bank 2
Bank 2
Bank 2
Bank 2
Bank 2
Bank 3
Bank 3
Bank 3
Location
Bank 2
Bank 2
Used in Equation 1. This value is programmed once at startup.
Equation 1 Value.
Description
Used in Equation 2. This value is programmed once at start up.
Used by Internal Adaptive Threshold Logic Only. The NEG_PEAK_DETECT is set to a
percentage of the difference between the ambient CDC value and the minimum
average CDC value. If the output of the CDC gets within the NEG_PEAK_DETECT
percentage of the minimum average, only then is the minimum average value updated.
Used by Internal Adaptive Threshold Logic Only. The POS_PEAK_DETECT is set to a
percentage of the difference between the ambient CDC value, and the maximum
average CDC value. If the output of the CDC gets within the POS_PEAK_DETECT
percentage of the minimum average, only then is the maximum average value updated.
Used in Equation 2. An initial value (based on sensor characterization) is programmed
into this register at startup. The AD7143 on-chip calibration algorithm automatically
updates this register based on the amount of sensor drift due to changing ambient
conditions. Set to 80% of the STAGE_OFFSET_LOW_CLAMP value.
Used in Equation 1. An initial value (based on sensor characterization) is programmed
into this register at startup. The AD7143 on-chip calibration algorithm automatically
updates this register based on the amount of sensor drift due to changing ambient
conditions. Set to 80% of the STAGE_OFFSET_HIGH_CLAMP value.
Used by Internal Environmental Calibration and Adaptive Threshold Algorithms Only.
An initial value (based on sensor characterization) is programmed into this register at
startup. The value in this register prevents a user from causing a sensor output value to
exceed the expected nominal value. Set to the maximum expected sensor response,
maximum change in CDC output code.
Used by Internal Environmental Calibration and Adaptive Threshold Algorithms Only.
An initial value (based on sensor characterization) is programmed into this register at
startup. The value in this register prevents a user from causing a sensor output value to
exceed the expected nominal value. Set to the minimum expected sensor response,
minimum change in CDC output code .
Used in Equation 1 and Equation 2. This is the ambient sensor output, when the sensor
is not touched, as calculated using the slow FIFO.
Equation 2 Value.
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