AD7150 Analog Devices, AD7150 Datasheet - Page 13

• Manufacturer Part Number: AD7150
• Description: Ultra-Low Power, 2-Channel, Capacitance Converter for Proximity Sensing
• Manufacturer: Analog Devices

Specifications of AD7150

• Resolution (bits): 12bit
• # Chan: 2
• Sample Rate: n/a
• Interface: I²C/Ser 2-Wire,Ser
• Analog Input Type: SE-Uni
• Ain Range: 0.5 pF,1 pF,2 pF,4 pF
• Adc Architecture: Sigma-Delta
• Pkg Type: SOP

AUTOCAPDAC ADJUSTMENT
In adaptive threshold mode, the part can dynamically adjust the
CAPDAC to keep the CDC in an optimal operating capacitive
range. When the AutoDAC function is enabled, the CAPDAC
value is automatically incremented when the data average
exceeds three-fourths of the CDC full range, and the CAPDAC
value is decremented when the data average goes below one-
fourth of the CDC full range. The AutoDAC increment or
decrement step depends on the selected CDC capacitive input
range. See the Setup Registers section.
POWER-DOWN TIMER
In power sensitive applications, the AD7150 can be set to
automatically enter power-down mode after a programmed
period of time in which the outputs have not been activated.
The AD7150 can be then returned to a normal operational
mode either via the serial interface or by the power supply
off/on sequence.
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POWER SUPPLY MONITOR
When the AD7150 V
defined level needed for correct CDC operation, the on-chip
power supply monitor stops the adaptive threshold logic and
holds it in reset. After the V
threshold logic is released, and the data average is reset to the
value of the first conversion finished at the correct power supply
voltage.
This feature prevents the adaptive threshold from being set
incorrectly after a very slow rise of the V
being corrupted by accidental drops in the V
The other AD7150 functions continue working below the
power supply monitor threshold, down to approximately
1.0V..1.8V, the exact level depending on the manufacturing
process variation. In the region of the low V
still accessible via the serial interface and continues conversion.
However, the conversion results may be incorrect and,
therefore, the data should not be considered valid if the part
operates below the power supply monitor threshold.
The status of the power supply monitor can be determined by
reading the PwrDown bit in the AD7150 status register.
DD
power supply voltage drops below a
DD
reaches the required level, the
DD
DD
voltage or from
voltage, the part is
DD
voltage.
AD7150