Overview
The AD694JN, 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 controlling valves, actuators, and other control devices, as well as transmitting process parameters such as pressure, temperature, or flow. It is a complete voltage-to-current transmitter, offering high accuracy and reliability in industrial process control, factory automation, and system monitoring applications.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Input Voltage Range | -0.2 VS | -2.0 V | -2.5 V | V |
| Input Bias Current | 1.5 | 5 | 5 | nA |
| Offset Current | ±0.1 | ±1 | ±1 | nA |
| Offset Current Drift | ±1.0 | ±5.0 | ±5.0 | pA/°C |
| Input Impedance | 5 | 5 | MΩ | |
| Operating Current Range | 0 | 23 | 23 | mA |
| Output Voltage Compliance | VS – 36 V | VS – 2 V | VS – 36 V | V |
| Output Impedance (4–20 mA) | 40.0 | 50.0 | 50.0 | MΩ |
| Current Limit (@ 2 × FS Overdrive) | 241 | 441 | 441 | mA |
| Slew Rate | 1.3 | 1.3 | mA/µs |
Key Features
- Precalibrated input ranges of 0 V to 2 V and 0 V to 10 V, selectable by pin strapping.
- Input amplifier configurable to buffer and scale the input voltage or serve as an output amplifier for current output DACs.
- Wide power supply range: +4.5 V to +36 V.
- Output voltage compliance extends to within 2 V of the positive supply and below common.
- Interfaces directly with 8-, 10-, and 12-bit single supply CMOS and bipolar DACs.
- 4 mA zero current can be switched on and off with a TTL control pin, allowing 0–20 mA operation.
- Open collector alarm for loop failure due to open wires or noncompliance of the output stage.
- Optional external pass transistor to reduce self-heating errors and extend the temperature range of operation.
- Precision voltage reference programmable to 2.000 V or 10.000 V.
Applications
The AD694JN is recommended for various applications in industrial process control, factory automation, and system monitoring. It is particularly useful for controlling valves, actuators, and other control devices, as well as for transmitting process parameters such as pressure, temperature, or flow. It serves as a replacement for discrete designs, offering improved reliability and performance in these applications.
Q & A
- What is the primary function of the AD694JN?
The AD694JN is a monolithic current transmitter that converts high-level signal inputs into a standard 4–20 mA current loop for controlling devices and transmitting process parameters.
- What are the precalibrated input ranges of the AD694JN?
The AD694JN has precalibrated input ranges of 0 V to 2 V and 0 V to 10 V, selectable by pin strapping.
- What is the power supply range for the AD694JN?
The AD694JN operates over a wide power supply range of +4.5 V to +36 V.
- How does the AD694JN handle output voltage compliance?
The output voltage compliance of the AD694JN extends to within 2 V of the positive supply and below common.
- Can the AD694JN be used with DACs?
Yes, the AD694JN interfaces directly with 8-, 10-, and 12-bit single supply CMOS and bipolar DACs.
- How is the 4 mA zero current controlled in the AD694JN?
The 4 mA zero current can be switched on and off with a TTL control pin, allowing 0–20 mA operation.
- What alarm feature does the AD694JN have?
The AD694JN includes an open collector alarm that warns of loop failure due to open wires or noncompliance of the output stage.
- How can the AD694JN reduce self-heating errors?
The AD694JN allows the use of an optional external pass transistor to reduce self-heating errors and extend the temperature range of operation.
- What temperature ranges are the AD694JN specified for?
The AD694JN is specified over the –40°C to +85°C industrial temperature range for hermetically sealed and SOIC packages, and 0°C to +70°C for the plastic DIP package.
- What types of packages are available for the AD694JN?
The AD694JN is available in hermetically sealed 16-pin CERDIP, plastic SOIC, and 16-pin plastic DIP packages.
- What is the precision of the voltage reference in the AD694JN?
The AD694JN has a precision voltage reference programmable to 2.000 V or 10.000 V.
