Overview
The AD694BRZ-REEL7, produced by Analog Devices Inc., is a monolithic current transmitter designed to convert high-level signal inputs into a standard 4-20 mA current loop. This component is ideal for systems requiring noise-immune signal transmission to operate valves, actuators, and other control devices. It is particularly useful in industrial process control, factory automation, and system monitoring applications. The AD694 is available in various packages, including hermetically sealed 16-pin CERDIP, plastic SOIC, and 16-pin plastic DIP, with specifications over different temperature ranges.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Input Voltage Range | -0.2 VS | - | -2.5 VS | V |
| Input Bias Current | 1.5 | 51 | 51 | nA |
| Offset Current | ± 0.1 | ±11 | ±11 | nA |
| Offset Current Drift | ± 1.0 | ± 5.0 | ± 5.0 | 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 | 50.0 | MΩ |
| Current Limit (@ 2 × FS Overdrive) | 241 | 441 | 441 | mA |
| Slew Rate | 1.3 | - | 1.3 | mA/µs |
| 4 mA Offset Error @ 0 V Input | ± 10 | ± 201 | ± 201 | µA |
| Trim Range, 4 mA Zero | 2.0 | - | 4.8 | mA |
Key Features
- Complete Voltage to 4-20 mA Current Transmitter: The AD694 converts high-level signal inputs into a standard 4-20 mA current loop.
- Pin Programmable Input Ranges: Pre-calibrated at 0 V to 2 V and 0 V to 10 V.
- Flexible Input Amplifier Configuration: Can be configured to buffer and scale the input voltage or serve as an output amplifier for current output DACs.
- Output Voltage Compliance: Extends to within 2 V of the positive supply and below common, with a compliance of up to 30 V below common when operated with a 5 V supply.
- Direct Interface with DACs: Interfaces directly with 8-, 10-, and 12-bit single supply CMOS and bipolar DACs.
- TTL Control for 4 mA Zero Current: The 4 mA zero current can be switched on and off using a TTL control pin, allowing 0-20 mA operation.
- Open Collector Alarm: Warns of loop failure due to open wires or non-compliance of the output stage.
- Monitored Output: Provides a monitored output to drive an external pass transistor, offloading power dissipation and extending the temperature range of operation.
Applications
- Industrial Process Control: Ideal for transmitting process parameters such as pressure, temperature, or flow in industrial environments.
- Factory Automation: Used in systems requiring noise-immune signal transmission to control valves, actuators, and other control devices.
- System Monitoring: Suitable for monitoring systems where reliable and accurate signal transmission is crucial.
Q & A
- What is the primary function of the AD694BRZ-REEL7?
The AD694BRZ-REEL7 is a monolithic current transmitter that converts high-level signal inputs into a standard 4-20 mA current loop.
- What are the available input voltage ranges for the AD694?
The input voltage ranges are pre-calibrated at 0 V to 2 V and 0 V to 10 V.
- What is the output voltage compliance of the AD694?
The output voltage compliance extends to within 2 V of the positive supply and below common, with up to 30 V below common when operated with a 5 V supply.
- Can the AD694 interface directly with DACs?
Yes, it interfaces directly with 8-, 10-, and 12-bit single supply CMOS and bipolar DACs.
- What is the purpose of the TTL control pin for the 4 mA zero current?
The TTL control pin allows the 4 mA zero current to be switched on and off, enabling 0-20 mA operation.
- How does the AD694 handle loop failure?
An open collector alarm warns of loop failure due to open wires or non-compliance of the output stage.
- What is the benefit of the monitored output feature?
The monitored output drives an external pass transistor, offloading power dissipation and extending the temperature range of operation.
- In what temperature ranges is the AD694 specified?
The AD694 is specified over the –40°C to +85°C industrial temperature range and 0°C to +70°C for certain packages.
- What are some common applications of the AD694?
Common applications include industrial process control, factory automation, and system monitoring.
- What packages is the AD694 available in?
The AD694 is available in hermetically sealed 16-pin CERDIP, plastic SOIC, and 16-pin plastic DIP packages.
