Overview
The AD694ARZ-REEL, produced by Analog Devices Inc., is a monolithic current transmitter designed to drive a standard 4–20 mA current loop. This device is ideal for systems that require noise-immune signal transmission to control valves, actuators, and other devices commonly used in process control. The AD694 accepts high-level signal inputs and features an input buffer amplifier that can scale the input signal or buffer the output from a current mode DAC. It offers precalibrated input ranges of 0 V to 2 V and 0 V to 10 V, which can be selected by simple pin strapping, and other spans can be programmed using external resistors.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Input Voltage Range | -0.2 VS | -2.0 V | VS - 2.5 V | V |
| Input Bias Current | 1.5 | 51 | 1.5 | nA |
| Offset Current | ± 0.1 | ±11 | ± 0.1 | nA |
| Offset Current Drift | ± 1.0 | ± 5.0 | ± 1.0 | pA/°C |
| Input Impedance | 5 | 5 | MΩ | |
| Operating Current Range | 0 | 23 | mA | |
| Output Voltage Compliance | VS – 36 V | VS – 2 V | V | |
| Output Impedance (4–20 mA) | 40.0 | 50.0 | MΩ | |
| Current Limit (@ 2 × FS Overdrive) | 241 | 441 | mA | |
| Slew Rate | 1.3 | 1.3 | mA/µs | |
| Span and Zero Accuracy - 4 mA Offset Error @ 0 V Input | ± 10 | ±201 | µA | |
| Trim Range, 4 mA Zero | 2.0 | 4.8 | mA | |
| Transfer Function Error from Nom, Input FS = 2 V, 10 V | ± 0.1 | ±0.31 | % of Span |
Key Features
- Precalibrated input ranges: 0 V to 2 V and 0 V to 10 V, with the option to program other spans using external resistors.
- Precision voltage reference programmable to 2.000 V or 10.000 V.
- Single or dual supply operation with a wide power supply range of 4.5 V to 36 V.
- Wide output compliance extending to within 2 V of VS.
- Input buffer amplifier for scaling the input signal or buffering the output from a current mode DAC.
- Open-loop alarm for detecting an open 4–20 mA loop or noncompliance of the output stage.
- Optional external pass transistor to reduce self-heating errors.
- High accuracy achieved through active laser trimming of thin film resistors.
Applications
The AD694ARZ-REEL is primarily used in process control systems to drive valves, actuators, and other devices. It is suitable for applications requiring noise-immune 4–20 mA signal transmission. Common use cases include industrial automation, control systems, and any environment where precise and reliable current loop control is necessary.
Q & A
- What is the primary function of the AD694ARZ-REEL?
The primary function of the AD694ARZ-REEL is to drive a standard 4–20 mA current loop for controlling valves, actuators, and other devices in process control systems. - What are the precalibrated input ranges of the AD694ARZ-REEL?
The precalibrated input ranges are 0 V to 2 V and 0 V to 10 V. - Can the AD694ARZ-REEL operate with a single or dual power supply?
Yes, the AD694ARZ-REEL can operate with either a single or dual power supply. - What is the power supply range for the AD694ARZ-REEL?
The power supply range is from 4.5 V to 36 V. - Does the AD694ARZ-REEL have an alarm feature?
Yes, it has an open-loop alarm to detect an open 4–20 mA loop or noncompliance of the output stage. - How does the AD694ARZ-REEL achieve high accuracy?
High accuracy is achieved through active laser trimming of the thin film resistors. - Can the AD694ARZ-REEL be used with an external pass transistor?
Yes, an optional external pass transistor can be used to reduce self-heating errors. - What is the typical nonlinearity of the AD694ARZ-REEL?
The typical nonlinearity is 0.002%. - What is the slew rate of the AD694ARZ-REEL?
The slew rate is 1.3 mA/µs. - What are common applications for the AD694ARZ-REEL?
Common applications include industrial automation, control systems, and any environment requiring precise and reliable current loop control.
