Overview
The AD7745ARUZ-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 is particularly suited for applications requiring high accuracy and linearity. The AD7745 features a single capacitance input channel, which can be configured as either single-ended or differential. It includes an on-chip temperature sensor, voltage reference, and clock generator, eliminating the need for external components in many capacitive sensor applications.
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 | Bits | No missing codes | ||
| Effective Resolution | 19 Bit | Bits | Conversion time = 62 ms | ||
| Output Noise, rms | 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 | ||
| 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 and Linearity: The AD7745 offers 24-bit no missing codes resolution with up to 21-bit effective resolution and high linearity (±0.01%).
- On-Chip Temperature Sensor: Includes a temperature sensor with a resolution of 0.1°C and accuracy of ±2°C.
- Voltage Reference and Clock Generator: On-chip voltage reference and clock generator eliminate the need for external components in many applications.
- Flexible Input Configuration: The capacitance input channel can be configured as single-ended or differential.
- Serial Interface: Supports an I2C-compatible 2-wire serial interface for easy communication with other devices.
- Power Efficiency: Operates with a single supply voltage from 2.7 V to 5.25 V and consumes only 0.7 mA of current.
Applications
- Automotive Systems: Suitable for pressure measurement, position sensing, and level sensing in automotive applications.
- Industrial Systems: Used in industrial settings for pressure measurement, position sensing, level sensing, flowmeters, humidity sensing, and impurity detection.
- Medical Systems: Applicable in medical devices for various sensing applications requiring high accuracy and reliability.
Q & A
- What is the resolution of the AD7745 capacitance-to-digital converter?
The AD7745 has a 24-bit no missing codes resolution with up to 21-bit effective resolution.
- What is the operating temperature range of the AD7745?
The operating temperature range is from –40°C to +125°C.
- Does the AD7745 have an on-chip temperature sensor?
Yes, it includes an on-chip temperature sensor with a resolution of 0.1°C and accuracy of ±2°C.
- What type of serial interface does the AD7745 support?
The AD7745 supports an I2C-compatible 2-wire serial interface.
- What is the power supply range for the AD7745?
The AD7745 operates with a single supply voltage from 2.7 V to 5.25 V.
- What is the current consumption of the AD7745?
The current consumption is approximately 0.7 mA.
- Can the AD7745 be used in automotive applications?
Yes, it is suitable for various automotive applications such as pressure measurement, position sensing, and level sensing.
- What package type is the AD7745 available in?
The AD7745 is available in a 16-lead TSSOP package.
- Does the AD7745 support simultaneous 50 Hz and 60 Hz rejection?
Yes, it supports simultaneous 50 Hz and 60 Hz rejection at 16 Hz.
- Can the AD7745 be used with floating capacitive sensors?
Yes, the AD7745 is designed for floating capacitive sensors.
