AD7156 Analog Devices, AD7156 Datasheet - Page 4

• Manufacturer Part Number: AD7156
• Manufacturer: Analog Devices

Specifications of AD7156

• Resolution (bits): 12bit
• # Chan: 2
• Sample Rate: 100SPS
• Interface: I²C/Ser 2-Wire,Ser
• Analog Input Type: Capacitive
• Ain Range: 0.5 pF,1 pF,2 pF,4 pF
• Pkg Type: CSP

AD7156
Parameter
POWER REQUIREMENTS
1
2
3
4
5
6
7
8
Capacitance units: 1 pF = 1 × 10
The CAPDAC can be used to shift (offset) the input range. The total capacitance of the sensor can therefore be up to the sum of the CAPDAC value and the conversion
input range. With the auto-DAC feature, the CAPDAC is adjusted automatically when the CDC input value is lower than 25% or higher than 75% of the CDC nominal
input range.
The maximum capacitance of the sensor connected between the EXCx and CINx pins is equal to the sum of the minimum guaranteed value of the CAPDAC and the
minimum guaranteed input range.
The maximum specification is not production tested but is supported by characterization data at initial product release.
The resolution of the converter is not limited by the output data format or output data LSB (least significant bit) size, but by the converter and system noise level. The
noise-free resolution is defined as level of peak-to-peak noise coming from the converter itself, with no connection to the CIN and EXC pins.
These specifications are understood separately. Any combination of the capacitance to ground and serial resistance may result in additional errors, for example gain
error, gain drift, offset error, offset drift, and power supply rejection.
Specification is not production tested but is guaranteed by design.
Digital inputs equal to V
V
I
I
DD
DD
DD
Current
Current Power-Down Mode
-to-GND Voltage
4, 8
DD
or GND.
−12
F; 1 fF = 10
4, 8
−15
F.
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Min
1.8
Typ
65
70
2
2
Max
3.6
75
85
10
17
Unit
V
μA
μA
μA
μA
1
Test Conditions/Comments
V
V
V
V
DD
DD
DD
DD
≤ 2.7 V, see Figure 20
= 3.6 V, see Figure 20
≤ 2.7 V, see Figure 21
= 3.6 V, see Figure 21