Overview
The AD7745ARUZ, produced by Analog Devices Inc., is a high-resolution, Σ-Δ capacitance-to-digital converter (CDC). This device is part of the AD7745/AD7746 series, which sets a new standard in single-chip solutions for capacitive sensing applications. The AD7745ARUZ is designed to interface directly with single or differential floating sensors, offering high resolution and accuracy in capacitance measurements.
The device features an on-chip temperature sensor, a voltage input channel, and an internal clock oscillator, making it a comprehensive solution for various capacitive sensing needs. It operates on a single supply voltage from 2.7 V to 5.25 V and consumes a low current of 0.7 mA, making it suitable for a wide range of applications.
Key Specifications
| Parameter | Min | Typ | Max | Unit | Test Conditions/Comments |
|---|---|---|---|---|---|
| Conversion Input Range | ±4.096 | pF | Factory calibrated | ||
| Integral Nonlinearity (INL) | ±0.01% | % of FSR | No missing codes | ||
| Resolution | 24 Bit | No missing codes | |||
| Effective Resolution | 19 Bit | Conversion time = 62 ms | |||
| Output Noise, rms | 2 aF/√Hz | See Table 5 | |||
| Absolute Error | ±4 fF | 25°C, VDD = 5 V, after offset calibration | |||
| Update Rate | 10 Hz | 90 Hz | |||
| Power Supply | 2.7 V | 5.25 V | Single-supply operation | ||
| Current Consumption | 0.7 mA | ||||
| Operating Temperature | –40°C | +125°C | |||
| Package | 16-lead TSSOP |
Key Features
- High resolution, Σ-Δ capacitance-to-digital converter (CDC) with up to 24-bit resolution and no missing codes.
- Interfaces directly with single or differential floating sensors.
- High accuracy and linearity: ±4 fF absolute error and ±0.01% linearity.
- Tolerant of parasitic capacitance to ground up to 60 pF.
- On-chip temperature sensor with 0.1°C resolution and ±2°C accuracy.
- Internal clock oscillator and voltage reference, eliminating the need for external components.
- 2-wire serial interface (I2C®-compatible).
- Simultaneous 50 Hz and 60 Hz rejection at 16 Hz update rate.
- Single-supply operation from 2.7 V to 5.25 V and low current consumption of 0.7 mA.
Applications
- Automotive systems: pressure measurement, position sensing, level sensing, flowmeters, and humidity sensing.
- Industrial systems: similar to automotive applications, including impurity detection.
- Medical systems: various capacitive sensing applications requiring high accuracy and reliability.
Q & A
- What is the resolution of the AD7745ARUZ?
The AD7745ARUZ has a resolution of up to 24 bits with no missing codes, and an effective resolution of 19 bits at a conversion time of 62 ms.
- What is the input range for the capacitance measurement?
The input range for the capacitance measurement is ±4.096 pF, factory calibrated.
- Does the AD7745ARUZ have an on-chip temperature sensor?
Yes, the AD7745ARUZ includes an on-chip temperature sensor with a resolution of 0.1°C and an accuracy of ±2°C.
- What is the power supply range for the AD7745ARUZ?
The AD7745ARUZ operates on a single supply voltage from 2.7 V to 5.25 V.
- What is the current consumption of the AD7745ARUZ?
The current consumption is 0.7 mA.
- What is the operating temperature range for the AD7745ARUZ?
The operating temperature range is from –40°C to +125°C.
- What type of package does the AD7745ARUZ come in?
The AD7745ARUZ comes in a 16-lead TSSOP package.
- Can the AD7745ARUZ reject 50 Hz and 60 Hz noise?
Yes, the AD7745ARUZ can reject both 50 Hz and 60 Hz noise simultaneously at a 16 Hz update rate.
- What are some common applications for the AD7745ARUZ?
Common applications include automotive, industrial, and medical systems for pressure measurement, position sensing, level sensing, flowmeters, and humidity sensing.
- Does the AD7745ARUZ support I2C communication?
Yes, the AD7745ARUZ has a 2-wire serial interface that is I2C-compatible.
