Overview
The AD8638ARJZ-REEL, produced by Analog Devices Inc., is a single, wide bandwidth, auto-zero operational amplifier. This device is notable for its rail-to-rail output swing, low noise, and high accuracy, making it suitable for applications where precision and minimal error are crucial. The AD8638 combines the benefits of low-cost, high-accuracy, and low-noise performance, previously found only in more expensive zero-drift or chopper-stabilized amplifiers. It operates over a wide supply voltage range of 5 V to 16 V single-supply or ±2.5 V to ±8 V dual-supply and does not require external capacitors.
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, all packages except SOT-23) | −40°C ≤ TA ≤ +125°C |
| Input Bias Current | 40 pA (maximum) | |
| Input Resistance | 22.5 TΩ | |
| Input Capacitance (Differential Mode) | 4 pF | |
| Output Voltage High | 4.97 V (RL = 10 kΩ to VCM) | −40°C ≤ TA ≤ +125°C |
| 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 |
Key Features
- Rail-to-Rail Output Swing: The AD8638 provides a full rail-to-rail output swing, ensuring maximum signal range and minimizing distortion.
- Low Noise and High Accuracy: With a typical offset voltage of 3 μV and drift of 0.01 μV/°C, this amplifier is highly accurate and suitable for precision applications.
- No External Capacitors Required: Unlike some other amplifiers, the AD8638 does not require external capacitors, simplifying the design and reducing component count.
- High Gain and CMRR/PSRR: The amplifier features high gain (136 dB typical), common-mode rejection ratio (CMRR) of 133 dB typical, and power supply rejection ratio (PSRR) of 143 dB typical.
- Low Supply Current: The AD8638 has a low supply current of 1.3 mA maximum, making it energy-efficient.
Applications
- Pressure and Position Sensors: The high accuracy and low noise of the AD8638 make it ideal for use in pressure and position sensors.
- Strain Gage Amplifiers: It is well-suited for strain gage amplifiers due to its low drift and high precision.
- Medical Instrumentation: The AD8638 is used in medical equipment where high accuracy and low noise are critical.
- Thermocouple Amplifiers: It is suitable for thermocouple amplifiers due to its low offset and drift characteristics.
- Automotive Sensors: The AD8639 variant is qualified for automotive applications, making it a reliable choice for automotive sensors.
- Precision References and Current Sensing: The amplifier’s high precision makes it suitable for precision references and current sensing applications.
Q & A
- What is the supply voltage range for the AD8638?
The AD8638 operates over a supply voltage range of 5 V to 16 V single-supply or ±2.5 V to ±8 V dual-supply.
- What is the typical offset voltage of the AD8638?
The typical offset voltage of the AD8638 is 3 μV.
- Does the AD8638 require external capacitors?
No, the AD8638 does not require external capacitors.
- What is the input bias current of the AD8638?
The input bias current of the AD8638 is 40 pA maximum.
- What are the key applications of the AD8638?
The AD8638 is used in pressure and position sensors, strain gage amplifiers, medical instrumentation, thermocouple amplifiers, automotive sensors, and precision references and current sensing.
- What is the gain bandwidth product of the AD8638?
The gain bandwidth product of the AD8638 is 1.35 MHz (RL = 2 kΩ, CL = 20 pF, AV = 1).
- What is the phase margin of the AD8638?
The phase margin of the AD8638 is 70 degrees (RL = 2 kΩ, CL = 20 pF, AV = 1).
- What is the voltage noise density at 1 kHz for the AD8638?
The voltage noise density at 1 kHz for the AD8638 is 60 nV/√Hz.
- Is the AD8638 suitable for automotive applications?
The AD8639 variant is qualified for automotive applications, but the AD8638 itself is not specifically qualified for automotive use.
- What is the operating temperature range of the AD8638?
The operating temperature range of the AD8638 is −40°C to +125°C.
