Overview
The AD693AD, produced by Analog Devices Inc., is a monolithic signal conditioning circuit designed to accept low-level inputs from various transducers and control a standard 4-20 mA, two-wire current loop. This device is particularly useful for transmitting low-level signals from RTDs, bridges, and pressure transducers. It features an on-chip voltage reference and an auxiliary amplifier, providing up to 3.5 mA of excitation current in loop-powered mode. The AD693AD is known for its high accuracy, achieved through active laser trimming of its thin-film resistors, and is suitable for applications in process control, factory automation, and system monitoring.
Key Specifications
| Parameter | Min | Typ | Max | Units |
|---|---|---|---|---|
| Input Span | 1 mV to 100 mV | - | - | mV |
| Output Span | 4-20 mA, 0-20 mA, 12 ± 8 mA | - | - | mA |
| Total Unadjusted Error (at +25°C) | ±0.25% | ±0.5% | - | % Full Scale |
| Total Unadjusted Error (TMIN to TMAX) | ±0.4% | ±0.75% | - | % Full Scale |
| Residual Nonlinearity | - | - | 0.05% | % |
| Auxiliary Amplifier Common-Mode Range | 0 | - | VOP - 4 V | V |
| Auxiliary Amplifier Input Offset Voltage | ±50 µV | ±200 µV | - | µV |
| Temperature Range (Case Operating) | -40°C | - | +85°C | °C |
| Temperature Range (Storage) | -65°C | - | +150°C | °C |
Key Features
- Precalibrated output zero and span options including 4-20 mA, 0-20 mA, and 12 ± 8 mA in two- and three-wire configurations.
- On-chip voltage reference and auxiliary amplifier for transducer excitation, providing up to 3.5 mA of current.
- Six precalibrated temperature ranges available with a 100 Ω RTD via pin strapping.
- High accuracy with total unadjusted error less than 0.5% of full scale at +25°C and less than 0.75% over the industrial temperature range.
- Residual nonlinearity under 0.05%.
- Optional external pass transistor to reduce self-heating errors.
Applications
The AD693AD is recommended for use in various applications including process control, factory automation, and system monitoring. It is particularly useful for transmitting low-level signals from RTDs, bridges, and pressure transducers. This device can replace discrete designs in these applications, offering a cost-effective signal conditioning solution.
Q & A
- What is the primary function of the AD693AD? The AD693AD is a monolithic signal conditioning circuit that converts low-level voltage inputs from transducers into a standard 4-20 mA current loop output.
- What are the precalibrated output spans available for the AD693AD? The precalibrated output spans include 4-20 mA, 0-20 mA, and 12 ± 8 mA in both two- and three-wire configurations.
- How much excitation current is available from the auxiliary amplifier? The auxiliary amplifier can provide up to 3.5 mA of excitation current when the device is operated in loop-powered mode.
- What is the temperature range for the AD693AD? The AD693AD is specified over the –40°C to +85°C industrial temperature range for case operating, and –65°C to +150°C for storage.
- What is the residual nonlinearity of the AD693AD? The residual nonlinearity is under 0.05%.
- Can the AD693AD be used with external pass transistors? Yes, the AD693AD allows for the use of an external pass transistor to reduce errors caused by self-heating.
- What types of transducers can the AD693AD support? The AD693AD can support RTDs, bridges, and pressure transducers.
- How is the accuracy of the AD693AD ensured? The accuracy is ensured through active laser trimming of the thin-film resistors, resulting in high levels of accuracy without additional adjustments and calibration.
- What are the common applications of the AD693AD? Common applications include process control, factory automation, and system monitoring.
- What are the packaging options for the AD693AD? The AD693AD is available in 20-pin ceramic side-brazed DIP, 20-pin Cerdip, and 20-pin LCCC packages.
