Overview
The AD8639ARMZ-R7, produced by Analog Devices Inc., is a dual-channel, auto-zero operational amplifier that combines high accuracy, low noise, and low cost. This amplifier features rail-to-rail output swing and is fully specified for operation from 5 V to 16 V single supply or ±2.5 V to ±8 V dual supply. It is particularly suited for applications requiring minimal error sources, such as precision instrumentation, medical equipment, and automotive sensors. The AD8639 is known for its very low offset voltage, drift, and bias current, making it an excellent choice for high-precision applications.
Key Specifications
| Parameter | Value | Conditions |
|---|---|---|
| Supply Voltage | 5 V to 16 V (single supply), ±2.5 V to ±8 V (dual supply) | |
| Offset Voltage | 3 μV (typical) | |
| Offset Voltage Drift | 0.01 μV/°C (typical), 0.04 μV/°C (SOT-23 package) | −40°C ≤ TA ≤ +125°C |
| Input Bias Current | 40 pA (maximum) | |
| Supply Current | 1.3 mA (maximum) | |
| Gain Bandwidth Product | 1.35 MHz | RL = 2 kΩ, CL = 20 pF, AV = 1 |
| Phase Margin | 70 Degrees | RL = 2 kΩ, CL = 20 pF, AV = 1 |
| Voltage Noise (0.1 Hz to 10 Hz) | 1.2 μV p-p | |
| Voltage Noise Density at 1 kHz | 60 nV/√Hz | |
| Input Resistance | 22.5 TΩ | |
| Input Capacitance (Differential Mode) | 4 pF | |
| Input Capacitance (Common Mode) | 1.7 pF | |
| Output Voltage High | 4.97 V (RL = 10 kΩ to VCM) | −40°C ≤ TA ≤ +125°C |
| Settling Time to 0.1% | 2.5 μs (VIN = 2 V step, CL = 20 pF, RL = 1 kΩ, AV = 1) | |
| Overload Recovery Time | 50 μs |
Key Features
- Rail-to-Rail Output Swing: The AD8639 provides full rail-to-rail output swing, ensuring maximum signal range and flexibility in various applications.
- Low Noise and Drift: With a typical offset voltage of 3 μV and drift of 0.01 μV/°C, this amplifier is ideal for high-precision applications where error sources must be minimized.
- High Gain and CMRR/PSRR: The amplifier offers high gain (136 dB typical), common-mode rejection ratio (CMRR) of 133 dB, and power supply rejection ratio (PSRR) of 143 dB, ensuring robust performance in noisy environments.
- Low Input Bias Current: The very low input bias current of 40 pA maximum reduces errors in high-impedance source applications.
- No External Capacitors Required: The auto-zero topology eliminates the need for external capacitors, simplifying circuit design and reducing component count.
- Automotive Qualification: The AD8639 is qualified for automotive applications, making it suitable for use in automotive sensors and other vehicle systems.
Applications
- Pressure and Position Sensors: The high precision and low noise of the AD8639 make it an excellent choice for sensor applications requiring accurate signal amplification.
- Strain Gage Amplifiers: Its low drift and high CMRR make it suitable for strain gage applications where precision is critical.
- Medical Instrumentation: The AD8639 is used in medical equipment due to its high accuracy and low noise, which are essential for precise medical measurements.
- Thermocouple Amplifiers: It is also used in thermocouple applications where low drift and high precision are necessary.
- Automotive Sensors: Qualified for automotive use, it is ideal for various automotive sensor applications.
- Precision References and Current Sensing: The amplifier’s high precision and low noise make it suitable for precision reference and current sensing applications.
Q & A
- What is the supply voltage range for the AD8639?
The AD8639 operates from 5 V to 16 V single supply or ±2.5 V to ±8 V dual supply.
- What is the typical offset voltage of the AD8639?
The typical offset voltage is 3 μV.
- What is the input bias current of the AD8639?
The input bias current is 40 pA maximum.
- Does the AD8639 require external capacitors?
No, the AD8639 does not require external capacitors due to its auto-zero topology.
- What are the key applications of the AD8639?
The AD8639 is used in pressure and position sensors, strain gage amplifiers, medical instrumentation, thermocouple amplifiers, automotive sensors, and precision references and current sensing.
- Is the AD8639 qualified for automotive applications?
Yes, the AD8639 is qualified for automotive applications.
- What is the gain bandwidth product of the AD8639?
The gain bandwidth product is 1.35 MHz (RL = 2 kΩ, CL = 20 pF, AV = 1).
- What is the phase margin of the AD8639?
The phase margin is 70 degrees (RL = 2 kΩ, CL = 20 pF, AV = 1).
- What is the typical voltage noise of the AD8639?
The typical voltage noise is 1.2 μV p-p (0.1 Hz to 10 Hz).
- What is the operating temperature range of the AD8639?
The operating temperature range is −40°C to +125°C.
