Overview
The AD7746ARUZ-REEL, produced by Analog Devices Inc., is a high-resolution, Σ-Δ capacitance-to-digital converter (CDC). This device is designed to measure capacitance directly and features inherent high resolution, high linearity, and high accuracy. The AD7746 is particularly suited for applications requiring precise capacitance measurements, such as pressure measurement, position sensing, level sensing, flowmeters, humidity sensing, and impurity detection. It operates with a single power supply from 2.7 V to 5.25 V and includes an on-chip temperature sensor and voltage input channel, making it versatile for various industrial, automotive, and medical systems.
Key Specifications
| Parameter | Min | Typ | Max | Unit | Test Conditions/Comments |
|---|---|---|---|---|---|
| Conversion Input Range | ±4.096 pF | pF | Factory calibrated | ||
| Integral Nonlinearity (INL) | ±0.01 % of FSR | % | No missing codes | ||
| Resolution | 24 Bit (no missing codes) | 21 Bit (effective resolution) | Bits | Conversion time = 62 ms | |
| Output Noise | 2 aF/√Hz | aF/√Hz | See Table 5 | ||
| Absolute Error | ±4 fF | fF | 25°C, VDD = 5 V, after offset calibration | ||
| Update Rate | 10 Hz | 90 Hz | Hz | ||
| Temperature Sensor Resolution | 0.1°C | °C | Accuracy: ±2°C | ||
| Power Supply | 2.7 V | 5.25 V | V | Single-supply operation | |
| Current Consumption | 0.7 mA | mA | |||
| Operating Temperature | –40°C | +125°C | °C | ||
| Package | 16-Lead TSSOP |
Key Features
- High-resolution, Σ-Δ capacitance-to-digital conversion with up to 21-bit effective resolution and no missing codes
- High linearity (±0.01%) and high accuracy (±4 fF factory calibrated)
- Capacitance input range of ±4 pF with tolerance for up to 60 pF parasitic capacitance to ground
- On-chip temperature sensor with 0.1°C resolution and ±2°C accuracy
- Voltage input channel and differential reference input for external temperature sensors
- 2-wire, I2C-compatible serial interface
- Internal clock oscillator and on-chip voltage reference
- Simultaneous 50 Hz and 60 Hz rejection at 16 Hz
- Programmable on-chip digital-to-capacitance converter (CAPDAC) for balancing common-mode capacitance
Applications
- Pressure measurement
- Position sensing
- Level sensing
- Flowmeters
- Humidity sensing
- Impurity detection
- Automotive systems
- Industrial systems
- Medical systems
Q & A
- What is the resolution of the AD7746 capacitance-to-digital converter?
The AD7746 has a resolution of up to 21-bit effective resolution with no missing codes.
- What is the operating temperature range of the AD7746?
The operating temperature range is from –40°C to +125°C.
- What is the power supply range for the AD7746?
The AD7746 operates with a single power supply from 2.7 V to 5.25 V.
- Does the AD7746 have an on-chip temperature sensor?
- What type of serial interface does the AD7746 use?
The AD7746 uses a 2-wire, I2C-compatible serial interface.
- What is the typical current consumption of the AD7746?
The typical current consumption is 0.7 mA.
- Can the AD7746 handle parasitic capacitance to ground?
- What are the common applications of the AD7746?
- Does the AD7746 support simultaneous 50 Hz and 60 Hz rejection?
- What package type is the AD7746 available in?
