AD8221ARZ - Precision Instrumentation Amplifier | Analog Devices
MPN: AD8221ARZ β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.86 | $4.86 |
| 10 | $4.36 | $43.60 |
| 100 | $3.88 | $388.00 |
| 500 | $3.49 | $1,745.00 |
| 1,000 | $3.29 | $3,290.00 |
Drop-in alternatives for AD8221ARZ β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
AD8221BRZ
β Drop-Inπ Reference alternative (not in catalog)
AD8221ARZ-RL
β Drop-Inπ Reference alternative (not in catalog)
AD8221ARZ-R7
β Drop-Inπ Reference alternative (not in catalog)
AD8422ARZ
β Drop-Inπ Reference alternative (not in catalog)
AD8223BRZ
β Drop-Inπ Reference alternative (not in catalog)
INA128UA
β Drop-Inπ Reference alternative (not in catalog)
AD8221ARZ Maximum Ratings & Electrical Characteristics
| Number of Channels | 1 |
| Gain Range | 1 to 1000 |
| Input Offset Voltage | 60 Β΅V (max) |
| Input Bias Current | 500 pA (max) |
| Bandwidth | 825 kHz (G=1) |
| Slew Rate | 2 V/Β΅s |
| CMRR | 90 dB (min) at 60 Hz, 80 dB (min) at 10 kHz |
| Supply Voltage Range | 4.5 V to 36 V (single), Β±2.25 V to Β±18 V (dual) |
| Quiescent Current | 1.2 mA (max) |
| Operating Temperature Range | -40Β°C to +85Β°C |
| Package | 8-Lead SOIC (R-8) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| REACH Status | Compliant |
| MSL Level | 1 (unlimited) |
AD8221ARZ Pin Configuration
| Pin 1 | RG β Gain setting resistor connection |
| Pin 2 | -IN β Inverting input |
| Pin 3 | +IN β Non-inverting input |
| Pin 4 | V- β Negative supply |
| Pin 5 | REF β Reference voltage for output level shifting |
| Pin 6 | OUT β Amplifier output |
| Pin 7 | V+ β Positive supply |
| Pin 8 | RG β Gain setting resistor connection |
Safe Operating Area (SOA) & Thermal Characteristics
No official SOA curve available for this component. Always operate within absolute maximum ratings specified in the datasheet. Ensure adequate cooling and derate as needed.
Typical Applications
AD8221ARZ is suitable for 6 applications: Medical Instrumentation (ECG/EEG), Industrial Process Control, Bridge Amplifier, Data Acquisition Systems, Precision Sensor Interface, Audio Test Equipment.
Medical Instrumentation (ECG/EEG)
The AD8221ARZ is ideal for ECG and EEG systems due to its low input offset voltage of 60 Β΅V and high CMRR of 90 dB at 60 Hz. These parameters ensure accurate amplification of bio-potential signals while rejecting power-line interference. The low input bias current of 500 pA minimizes loading on high-impedance electrodes, preserving signal integrity. In an ECG front-end, the AD8221ARZ amplifies the differential signal from electrodes, providing a clean output for further processing. Its bandwidth of 825 kHz is sufficient for ECG signals, which are typically below 100 Hz. The device's low power consumption (1.2 mA) is beneficial for portable monitors. For optimal performance, use shielded cables and proper grounding to maintain high CMRR.
Recommended
Industrial Process Control
In industrial process control, the AD8221ARZ provides precise amplification of sensor signals from bridges, thermocouples, and strain gauges. Its high CMRR of 80 dB at 10 kHz rejects common-mode noise from long cable runs and motor drives. The gain range of 1 to 1000 allows flexible scaling of sensor outputs to match ADC input ranges. The device operates from a wide supply range (up to 36 V), making it compatible with 24 V industrial buses. Its low offset voltage (60 Β΅V) ensures accurate measurement of small sensor signals. The AD8221ARZ's robust design and wide temperature range (-40Β°C to +85Β°C) make it suitable for harsh factory environments. For best results, use twisted-pair wiring and proper shielding to minimize electromagnetic interference.
Recommended
Bridge Amplifier
The AD8221ARZ is well-suited for bridge amplifier applications, such as load cells and pressure sensors. Its low input bias current (500 pA) minimizes errors caused by source impedance imbalance in bridge circuits. The high CMRR ensures that common-mode voltage variations, often present in bridge excitation, are rejected. The gain is easily set with a single resistor, allowing calibration for different bridge sensitivities. The device's bandwidth of 825 kHz supports dynamic measurements, such as vibration monitoring. The AD8221ARZ's low offset voltage (60 Β΅V) reduces zero-error, improving measurement accuracy. For bridge applications, use precision resistors for the bridge and a stable excitation voltage to achieve optimal performance.
Recommended
Data Acquisition Systems
In data acquisition systems, the AD8221ARZ conditions analog signals before ADC conversion. Its low noise and high bandwidth (825 kHz) preserve signal fidelity, while the gain range allows matching signal levels to ADC input ranges. The high CMRR reduces interference from digital circuits and power supplies. The device's small SOIC package enables dense PCB layouts in multi-channel systems. The AD8221ARZ's low power consumption (1.2 mA) is advantageous for portable data loggers. For high-resolution measurements, pair the AD8221ARZ with a high-resolution ADC and use proper anti-aliasing filters. The device's wide supply range supports various system power architectures.
Recommended
Precision Sensor Interface
The AD8221ARZ is ideal for precision sensor interfaces, including temperature, pressure, and position sensors. Its low offset voltage (60 Β΅V) and low bias current (500 pA) ensure accurate signal conditioning from high-impedance sensors. The high CMRR rejects common-mode noise, which is critical in noisy environments. The gain range of 1 to 1000 allows amplification of small sensor signals to usable levels. The device's wide supply range and low power consumption make it suitable for battery-powered sensors. For optimal performance, use a stable reference voltage and proper PCB layout to minimize parasitic capacitance. The AD8221ARZ's small package and surface-mount design facilitate integration into compact sensor modules.
Recommended
Audio Test Equipment
The AD8221ARZ can be used in audio test equipment for measuring differential signals with high accuracy. Its low distortion and high bandwidth (825 kHz) make it suitable for audio frequency range measurements. The high CMRR ensures rejection of common-mode noise, which is important in balanced audio connections. The gain range allows adjusting sensitivity for different signal levels. The device's low noise performance is critical for audio measurements. The AD8221ARZ's small package and low power consumption are beneficial for portable test instruments. For audio applications, use high-quality input coupling capacitors and proper shielding to minimize interference.
Recommended
Recommended Products Summary
Engineering reference data for AD8221ARZ β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | AD8221BRZ | AD8422ARZ | AD8223BRZ | INA128UA |
|---|---|---|---|---|---|
| Package | 8-Lead SOIC | 8-Lead SOIC | 8-Lead SOIC | 8-Lead SOIC | 8-Lead SOIC |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Texas Instruments |
| Input Offset Voltage | 60 Β΅V (max) | 25 Β΅V (max) | 60 Β΅V (max) | 150 Β΅V (max) | 50 Β΅V (max) |
| Input Bias Current | 500 pA (max) | 500 pA (max) | 500 pA (max) | 500 pA (max) | 5 nA (max) |
| Bandwidth | 825 kHz | 825 kHz | 2.2 MHz | 200 kHz | 200 kHz |
| CMRR at 60 Hz | 90 dB (min) | 100 dB (min) | 90 dB (min) | 80 dB (min) | 90 dB (min) |
| Supply Voltage Range | 4.5 V to 36 V | 4.5 V to 36 V | 4.5 V to 36 V | 4.5 V to 36 V | 4.5 V to 36 V |
| Quiescent Current | 1.2 mA (max) | 1.2 mA (max) | 1.2 mA (max) | 1.2 mA (max) | 700 Β΅A (max) |
Key Differentiators
- Highest CMRR over frequency in its class (vs AD8223BRZ)
- Low input bias current of 500 pA (vs INA128UA)
- Wide bandwidth of 825 kHz (vs AD8223BRZ)
Design Notes
For optimal CMRR, ensure a solid ground plane and place decoupling capacitors (0.1 Β΅F ceramic and 10 Β΅F tantalum) close to the supply pins. Use guard traces around the inputs to minimize leakage currents. The reference pin (pin 5) should be bypassed with a capacitor to ground to reduce noise.
The gain resistor (RG) must be a precision resistor (0.1% tolerance or better) to maintain gain accuracy. Avoid using long traces for RG connections, as parasitic capacitance can affect bandwidth. Also, ensure the input common-mode voltage is within the specified range to avoid output saturation.
The AD8221ARZ dissipates minimal power (typically less than 50 mW), so thermal management is not critical. However, in high-temperature environments, ensure the junction temperature stays below 150Β°C. The SOIC package has a thermal resistance of approximately 100Β°C/W, so adequate airflow or copper pour is recommended for high ambient temperatures.
Compliance Information
RoHS and REACH compliance confirmed from Analog Devices product page. AEC-Q100 not applicable as this is not an automotive-grade part.
