Overview
The AD8494CRMZ-R7, produced by Analog Devices Inc., is a precision instrumentation amplifier with a thermocouple cold junction compensator integrated into a single IC package. This device is specifically designed to work with J-type (iron-constantan) thermocouples. It produces a high-level output (5 mV/°C) directly from the thermocouple signal, combining an ice point reference with a precalibrated amplifier. The AD8494CRMZ-R7 can be used as a standalone thermometer or as a switched output setpoint controller, offering flexibility in various temperature measurement applications.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Supply Voltage Range | 2.7 to 36 | V |
| Output Voltage Range | -VS + 0.025 to +VS - 0.1 | V |
| Input Voltage Range | -VS - 0.2 to +VS - 1.6 | V |
| Overvoltage Range | +VS - 25 to -VS + 25 | V |
| Input Bias Current | 25 to 50 | nA |
| Input Offset Current | 1.5 to 0.5 | nA |
| Common-Mode Rejection | 1 to 0.3 | °C/V |
| Power Supply Rejection | 0.5 to 0.5 | °C/V |
| Voltage Noise (0.1 Hz to 10 Hz) | 0.8 | μV p-p |
| Voltage Noise Density (1 kHz) | 32 | nV/√Hz |
| Current Noise Density (1 kHz) | 100 | fA/√Hz |
| Reference Input Resistance | 60 | kΩ |
| Reference Input Current | 25 | μA |
| Output Short-Circuit Current | 7 | mA |
| -3 dB Bandwidth | 30 | kHz |
| Settling Time to 0.1% (4 V output step) | 36 | μs |
Key Features
- Precision Instrumentation Amplifier: The AD8494CRMZ-R7 is a precision instrumentation amplifier designed for thermocouple applications, providing a high-level output of 5 mV/°C.
- Cold Junction Compensation: It includes an integrated cold junction compensator, ensuring accurate temperature measurements by compensating for the temperature at the cold junction of the thermocouple.
- Flexible Supply Voltage: The device can operate with a wide range of supply voltages from 2.7 V to 36 V, making it suitable for various applications, including those requiring low power and those needing a wide common-mode input range.
- Rugged Inputs: The inputs are robust, withstanding 4 kV ESD and providing overvoltage protection up to ±25 V relative to the supply voltage.
- Differential Inputs: Differential inputs help reject common-mode noise on the thermocouple leads, enhancing signal integrity.
- Reference Pin Offset: The reference pin voltage can be offset to measure temperatures below 0°C on single supplies.
- Compact Package: Available in a small, 8-lead MSOP package that is fully RoHS compliant.
Applications
- Industrial Temperature Measurement: Suitable for industrial systems requiring precise temperature measurements over a wide range.
- Process Control: Can be used as a standalone thermometer or as a setpoint controller in process control applications.
- Aerospace and Automotive: Applicable in aerospace and automotive industries where reliable and precise temperature monitoring is critical.
- Medical Devices: Used in medical devices that require accurate temperature measurements.
- Environmental Monitoring: Ideal for environmental monitoring systems that need to measure temperatures accurately in various conditions.
Q & A
- What type of thermocouple does the AD8494CRMZ-R7 support?
The AD8494CRMZ-R7 is precalibrated to match the characteristics of J-type (iron-constantan) thermocouples.
- What is the output voltage range of the AD8494CRMZ-R7?
The output voltage range is from -VS + 0.025 V to +VS - 0.1 V.
- What is the supply voltage range for the AD8494CRMZ-R7?
The device can operate with supply voltages ranging from 2.7 V to 36 V.
- How does the AD8494CRMZ-R7 handle common-mode noise?
The device has differential inputs that reject common-mode noise on the thermocouple leads.
- What is the typical settling time of the AD8494CRMZ-R7?
The settling time to 0.1% for a 4 V output step is typically 36 μs.
- Is the AD8494CRMZ-R7 ESD protected?
Yes, the inputs are protected against 4 kV ESD.
- What is the package type of the AD8494CRMZ-R7?
The device is available in an 8-lead MSOP package.
- Can the AD8494CRMZ-R7 measure temperatures below 0°C?
Yes, by offsetting the reference input, the device can measure temperatures below 0°C on single supplies.
- What is the typical power supply rejection ratio of the AD8494CRMZ-R7?
The power supply rejection ratio is typically 0.5 °C/V.
- Is the AD8494CRMZ-R7 RoHS compliant?
Yes, the device is fully RoHS compliant.
