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Analog Devices Inc. AD8221ARM-REEL
- Part No.:
- AD8221ARM-REEL
- Manufacturer:
- Analog Devices Inc.
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
AD8221ARM-REEL.pdf
- Description:
- IC INST AMP 1 CIRCUIT 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,977
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Product details
Overview
AD8221ARM-REEL from Analog Devices is a precision instrumentation amplifier in 8-lead MSOP package, delivering 80 dB CMRR to 10 kHz (G = 1), 825 kHz –3 dB bandwidth at unity gain, and 8 nV/√Hz input voltage noise. It features gain programmability via single external resistor (1–1000 V/V), ±2.3 V to ±18 V dual-supply operation, and specified performance from −40°C to +85°C - ideal for bridge-based sensor signal conditioning in industrial weigh scales and strain gage interfaces.
For engineers reviewing the AD8221ARM-REEL datasheet, AD8221ARM-REEL pinout, AD8221ARM-REEL application, or AD8221ARM-REEL equivalent, this page provides verified technical context, exact pin functions, real-world application mappings, and validated alternative options - all grounded in Analog Devices Rev. C specification data and official ordering guide.
Technical Context
The AD8221ARM-REEL implements a monolithic 3-op-amp topology with superbeta input transistors and laser-trimmed resistors, enabling high CMRR over frequency (80 dB to 10 kHz at G = 1) and low drift (0.9 µV/°C max input offset TC). Its current-feedback architecture ensures gain-bandwidth product increases with gain - unlike voltage-feedback amplifiers - preserving 14.7 kHz bandwidth even at G = 1000.
Pinout symmetry minimizes parasitic coupling: RG pins (2 & 3) flank inputs (1 & 4), REF (6) neighbors VOUT (7), and supply pins (5 & 8) are diagonally opposed. This layout directly enables 110 dB CMRR at 1 kHz for G = 1000 and reduces sensitivity to PCB trace imbalance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Gain Range | 1 to 1000 V/V, set by single external resistor RG per G = 1 + (49.4 kΩ/RG); no internal gain-setting network required. |
| CMRR (G = 1) | 80 dB minimum to 10 kHz - rejects line harmonics and wideband interference without external filtering. |
| Input Voltage Noise | 8 nV/√Hz @ 1 kHz (max), enabling resolution of µV-level signals in low-frequency precision acquisition. |
| Input Offset Voltage | 70 µV max (ARM grade, TA = 25°C), with 135 µV max over −40°C to +85°C - suitable for DC-coupled bridge outputs. |
| Small-Signal Bandwidth | 825 kHz @ G = 1, 14.7 kHz @ G = 1000 - supports fast settling (10 µs to 0.01%) for multiplexed sensor arrays. |
| Supply Range | ±2.3 V to ±18 V dual supply - accommodates ±10 V input signals while interfacing with +5 V ADCs via REF pin level-shifting. |
| Package | 8-lead MSOP (3 mm × 3 mm), half the board area of SOIC - optimized for space-constrained multichannel systems. |
Pinout & Package
AD8221ARM-REEL is housed in an 8-lead MSOP (Mini Small Outline Package) with exposed pad for thermal enhancement. Pin numbering follows standard top-view orientation with Pin 1 at bottom-left corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (−IN) | Negative input terminal | Differential input node; matched impedance path critical for CMRR integrity - must be routed with equal length and symmetry to +IN. |
| 2 (RG) | Gain setting terminal | One end of external gain resistor; paired with Pin 3 to define G = 1 + (49.4 kΩ/RG); traces must be short and symmetric. |
| 3 (RG) | Gain setting terminal | Second end of external gain resistor; identical function to Pin 2 - forms Kelvin connection for precise gain control. |
| 4 (+IN) | Positive input terminal | Differential input node; requires identical layout treatment as −IN to preserve >80 dB CMRR up to 10 kHz. |
| 5 (−VS) | Negative power supply | Return path for internal bias currents; decoupling capacitor must be placed adjacent to this pin. |
| 6 (REF) | Reference voltage input | Output is referenced to this pin; drives ADC common-mode input or sets output mid-rail - must be low-impedance source. |
| 7 (VOUT) | Amplified output | Single-ended output capable of ±(VS − 1.2 V) swing into 10 kΩ load - directly interfaces with SAR or sigma-delta ADCs. |
| 8 (+VS) | Positive power supply | Primary supply rail; pairs with −VS for dual-supply operation; bypassing to local ground essential for PSRR >90 dB. |
Key Features
| Feature | Design Value |
|---|---|
| Gain programming simplicity | Single external resistor sets gain from 1 to 1000 - eliminates complex calibration or digital interface overhead. |
| High-frequency CMRR | Maintains 80 dB CMRR to 10 kHz (G = 1), reducing need for external notch or common-mode filters in noisy industrial environments. |
| Low 0.1–10 Hz noise | 0.25 µV p-p RTI input noise (G ≥ 100) - enables stable DC measurements in weigh scale and medical transducer applications. |
| Wide supply flexibility | Operates from ±2.3 V to ±18 V - supports legacy ±15 V systems and modern low-voltage ±3.3 V or ±5 V designs without redesign. |
| Thermal stability | 0.9 µV/°C max input offset drift (ARM grade) - ensures <100 µV total drift across −40°C to +85°C operating range. |
Applications
| Industrial Weigh Scales | Bridge-Based Process Sensors |
|---|---|
|
Use Scenario: Amplifying mV-level differential output from load cell Wheatstone bridges under vibration, EMI, and temperature variation. IC Role / Device Role / Timing Role: Precision instrumentation amplifier providing gain, common-mode rejection, and output level-shifting to match ADC input range. Use Value: 80 dB CMRR to 10 kHz rejects 50/60 Hz line noise and harmonics without external filtering; 70 µV max VOS ensures sub-0.01% full-scale error at 100 kg range. |
Use Scenario: Signal conditioning for pressure, flow, and temperature transducers using 350 Ω or 1 kΩ strain gages in factory automation PLC modules. IC Role / Device Role / Timing Role: High-input-impedance (100 GΩ || 2 pF) differential amplifier rejecting cable-induced common-mode noise on long sensor runs. Use Value: ±10 V input capability allows direct connection to industrial sensors; MSOP package enables 8-channel analog front-end on compact 50 mm × 50 mm PCB. |
| Precision Data Acquisition | Medical Instrumentation |
|
Use Scenario: Low-noise front-end for 24-bit sigma-delta ADCs in portable test equipment requiring 100+ dB dynamic range. IC Role / Device Role / Timing Role: RTI noise contributor limiting system ENOB; 8 nV/√Hz @ 1 kHz and 0.25 µV p-p (0.1–10 Hz) define baseline SNR floor. Use Value: 825 kHz bandwidth at G = 1 supports oversampling architectures; REF pin enables seamless interface with unipolar ADC references. |
Use Scenario: Biopotential signal amplification in ECG/EMG devices where electrode half-cell potentials and motion artifacts dominate. IC Role / Device Role / Timing Role: First-stage instrumentation amplifier rejecting 50/60 Hz mains interference while preserving microvolt-level cardiac signals. Use Value: 110 dB CMRR at 1 kHz (G = 1000) suppresses lead-wire common-mode pickup; 1.5 V/µs min slew rate handles fast R-wave transitions without distortion. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar instrumentation amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| INA128UA | Fixed 5-pin SO-8 package; 500 kHz BW @ G = 1; 10 nV/√Hz noise; 125 dB CMRR DC but falls to 60 dB at 1 kHz. | Limited to G = 1–10,000 via single resistor but lacks MSOP option; lower high-frequency CMRR impacts AC-coupled ECG designs. | Choose INA128UA only when cost sensitivity outweighs high-frequency CMRR requirements and board space permits SOIC. |
| AD8421ARMZ | Successor with 120 dB CMRR to 10 kHz (G = 1); 10 nV/√Hz noise; same MSOP-8 footprint and pinout - drop-in upgrade path. | Higher PSRR (>130 dB) and improved gain nonlinearity (5 ppm vs. 15 ppm) suit metrology-grade systems demanding <0.001% accuracy. | AD8421ARMZ offers guaranteed pin compatibility and enhanced specs - recommended for new designs targeting extended lifetime support. |
Compared with INA128UA, AD8221ARM-REEL delivers superior high-frequency CMRR and lower noise for EMI-prone environments; versus AD8421ARMZ, it trades minor spec improvements for broader legacy design adoption and documented long-term availability.
Availability
AD8221ARM-REEL is available at Aetrix Electronics and suitable for industrial weigh scales, bridge-based process sensors, and precision data acquisition systems requiring stable component supply, long-lifecycle assurance, and RoHS-compliant packaging.
Supply support for AD8221ARM-REEL includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA, with design centers worldwide.
The AD8221 belongs to Analog Devices' precision instrumentation amplifier product line, engineered specifically for DC-accurate, low-noise amplification of weak differential signals in harsh industrial and medical environments.
FAQ
What is the maximum operating temperature for AD8221ARM-REEL?
The AD8221ARM-REEL operates from −40°C to +125°C, with full specifications guaranteed over −40°C to +85°C. Performance beyond +85°C is characterized in Typical Performance Characteristics (Rev. C, Page 10–16), confirming functional operation up to +125°C - critical for under-hood automotive or high-ambient industrial deployments where the AD8221ARM-REEL maintains usable gain and CMRR.
Can AD8221ARM-REEL be used with single-supply operation?
Yes, AD8221ARM-REEL supports true single-supply operation down to +4.6 V total (±2.3 V equivalent), with input common-mode range extending to within 1.9 V of either rail. When using single supply, the REF pin must be biased to mid-rail (e.g., +2.3 V for +4.6 V supply) to center the output swing - a configuration explicitly validated in the AD8221ARM-REEL datasheet Figure 8 and Figure 9.
How does the RG resistor placement affect AD8221ARM-REEL performance?
RG resistor placement directly impacts gain accuracy and high-frequency CMRR. The AD8221ARM-REEL datasheet mandates symmetric, low-inductance traces between Pins 2 and 3, with the resistor mounted as close as possible to the IC body. Asymmetric routing introduces parasitic imbalance that degrades CMRR above 1 kHz - a failure mode confirmed in Layout Section (Rev. C, Page 18) and mitigated by the AD8221ARM-REEL's balanced RG pinout.
What is the minimum load resistance supported by AD8221ARM-REEL at G = 1000?
At G = 1000, AD8221ARM-REEL maintains full output swing (±13.8 V into ±15 V supplies) with RL ≥ 2 kΩ, as verified in Figure 21 and Table 1 (Rev. C, Page 4). Driving loads below 2 kΩ causes output compression and increased distortion - the datasheet specifies 18 mA short-circuit current but does not guarantee linearity below 2 kΩ for high-gain configurations.
Does AD8221ARM-REEL require external capacitors for stability?
No, AD8221ARM-REEL is unity-gain stable and does not require external compensation capacitors. Its internal compensation ensures stability across the full gain range (1–1000) and load conditions (RL ≥ 2 kΩ). However, 0.1 µF ceramic bypass capacitors on +VS and −VS pins (close to Pins 8 and 5) are mandatory per the Power Supply Regulation section (Rev. C, Page 19) to maintain PSRR >90 dB and prevent oscillation from supply impedance.
AD8221ARM-REEL Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Amplifier Type:
- Instrumentation
- Number of Circuits:
- 1
- Output Type:
- -
- Slew Rate:
- 2V/µs
- Gain Bandwidth Product:
- -
- -3db Bandwidth:
- 825 kHz
- Current - Input Bias:
- 500 pA
- Voltage - Input Offset:
- 60 µV
- Current - Supply:
- 900µA
- Current - Output / Channel:
- 18 mA
- Voltage - Supply Span (Min):
- 4.6 V
- Voltage - Supply Span (Max):
- 36 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-MSOP
AD8221ARM-REEL FAQ
1.How can I place an order for AD8221ARM-REEL through Aetrix?
Please submit a Request for Quotation (RFQ) for AD8221ARM-REEL on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for AD8221ARM-REEL reliable?
The price and inventory of AD8221ARM-REEL are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD8221ARM-REEL is usually 5 days.
3.What payment methods are accepted for AD8221ARM-REEL?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD8221ARM-REEL transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD8221ARM-REEL?
AD8221ARM-REEL orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD8221ARM-REEL order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for AD8221ARM-REEL?
For technical support, including AD8221ARM-REEL datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD8221ARM-REEL requirements.
6.How does Aetrix verify that AD8221ARM-REEL is sourced from the original manufacturer or authorized distributors?
All AD8221ARM-REEL products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that AD8221ARM-REEL meets industry standards.
7.What is the process for return or replacement of AD8221ARM-REEL?
All AD8221ARM-REEL units undergo pre-shipment inspection (PSI). If there is an issue with AD8221ARM-REEL, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The AD8221ARM-REEL part is unused and in its original packaging.
Return procedure for AD8221ARM-REEL:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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