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Analog Devices Inc. AD8421BRZ
- Part No.:
- AD8421BRZ
- Manufacturer:
- Analog Devices Inc.
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
AD8421BRZ.pdf
- Description:
- IC INST AMP 1 CIRCUIT 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:9,104
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Product details
Overview
AD8421BRZ from Analog Devices is a high-precision, low-power instrumentation amplifier with 3.2 nV/√Hz input voltage noise, 94 dB minimum CMRR at G = 1, and 0.2 µV/°C max input offset voltage drift. It operates from ±2.5 V to ±18 V dual supply, features single-resistor gain setting (G = 1 to 10,000), and is used in medical instrumentation and precision data acquisition systems where low-level signal integrity is critical.
For engineers reviewing the AD8421BRZ datasheet, AD8421BRZ pinout, AD8421BRZ application, or AD8421BRZ equivalent, this page delivers verified specifications, package mapping to 8-lead SOIC, real-world use scenarios, and two validated alternative parts for design flexibility and supply continuity.
Technical Context
The AD8421BRZ employs a current-feedback architecture that maintains 2 MHz bandwidth at G = 100 and achieves 0.6 µs settling time to 0.001% - enabling high-channel-count, multiplexed data acquisition. Its input stage uses proprietary protection allowing ±40 V input overvoltage tolerance relative to opposite supply rail without damage.
It integrates a reference input terminal for precise output level shifting, supports differential output configuration, and delivers ultralow bias current (500 pA max) with 30 GΩ||3 pF input impedance - essential for high-source-impedance sensor interfaces like strain gauges and piezoelectric transducers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Noise | 3.2 nV/√Hz at 1 kHz - enables accurate measurement of microvolt-level signals in low-noise front ends. |
| CMRR (min) | 94 dB at G = 1, DC–60 Hz - rejects common-mode interference from ECG electrodes or industrial sensors. |
| Input Offset Drift | 0.2 µV/°C max - ensures stable baseline in temperature-varying environments like patient monitors. |
| Gain Range | 1 to 10,000 via single external resistor - simplifies calibration and supports wide dynamic range in programmable gain amplifiers. |
| Supply Current | 2.3 mA max - allows battery-powered portable instrumentation with multi-hour operation. |
| Bandwidth (G = 100) | 2 MHz - supports vibration analysis up to ~300 kHz with adequate phase margin. |
| Slew Rate | 35 V/µs - handles fast transient signals from accelerometers without distortion. |
Pinout & Package
The AD8421BRZ is packaged in an 8-lead SOIC (Small Outline Integrated Circuit) with exposed pad, rated for −40°C to +85°C operation. Thermal resistance θJA is 107.8°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (−IN) | Negative Input Terminal | Differential input node; connects to low-side sensor terminal or bridge leg. |
| 2, 3 (RG) | Gain Setting Terminals | Resistor across these pins sets gain per G = 1 + (9.9 kΩ/RG); no internal resistor required. |
| 4 (+IN) | Positive Input Terminal | Differential input node; connects to high-side sensor terminal or bridge leg. |
| 5 (−VS) | Negative Power Supply | Connects to negative rail; exposed pad may be tied to −VS for thermal performance. |
| 6 (REF) | Reference Input | Low-impedance voltage source applied here shifts output DC level without affecting gain accuracy. |
| 7 (VOUT) | Amplified Output | Drives ADC inputs or downstream filters; capable of ±13.4 V swing on ±15 V supplies. |
| 8 (+VS) | Positive Power Supply | Connects to positive rail; decoupling capacitor required near pin for stability. |
Key Features
| Feature | Design Value |
|---|---|
| Input Overvoltage Protection | Withstands ±40 V beyond opposite supply rail - eliminates need for external clamping diodes in industrial sensor interfaces. |
| Ultralow Input Bias Current | 500 pA max - prevents signal degradation when interfacing with >100 MΩ source impedances (e.g., pH electrodes). |
| Single-Supply Compatibility | Operates from 5 V to 36 V - supports direct integration into 5 V or 24 V industrial PLC I/O modules. |
| High CMRR Stability | 80 dB CMRR maintained at 20 kHz (G = 1) - preserves signal fidelity in presence of high-frequency switching noise. |
| Reference Terminal Flexibility | 1 ppm/V reference gain accuracy - enables precise ratiometric offset correction in bridge-based load cell systems. |
Applications
| Medical Instrumentation | Precision Data Acquisition |
|---|---|
Use Scenario: Amplifying low-amplitude biopotential signals (e.g., ECG, EEG) from dry electrodes with high common-mode interference. IC Role / Device Role / Timing Role: Front-end instrumentation amplifier providing differential gain, CMRR filtering, and rail-to-rail output drive capability. Use Value: 94 dB min CMRR and 3.2 nV/√Hz noise ensure diagnostic-grade signal clarity without additional shielding or guard traces. | Use Scenario: Conditioning outputs from strain gauge bridges in structural health monitoring systems deployed outdoors. IC Role / Device Role / Timing Role: Precision gain stage with reference input for zero-point calibration and temperature-compensated offset trimming. Use Value: 0.2 µV/°C input offset drift and 1 ppm/°C gain drift maintain measurement accuracy across −40°C to +85°C ambient range. |
| Vibration Analysis | ADC Driver |
Use Scenario: Signal conditioning for piezoelectric accelerometers in predictive maintenance equipment sampling at 100 kSPS. IC Role / Device Role / Timing Role: High-bandwidth, low-distortion amplifier driving anti-aliasing filter before SAR ADC. Use Value: 2 MHz bandwidth at G = 100 and 0.6 µs settling time support accurate capture of 50 kHz mechanical resonance peaks. | Use Scenario: Driving the analog input of a 16-bit SAR ADC (e.g., AD7685) in a portable multimeter with auto-ranging. IC Role / Device Role / Timing Role: Low-noise, low-output-impedance buffer ensuring full-scale accuracy and minimal code transition errors. Use Value: 35 V/µs slew rate and 60 nV/√Hz output noise prevent harmonic distortion and quantization uncertainty at full scale. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar instrumentation amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| INA828IDR | Lower input bias current (1 pA typ), higher CMRR (130 dB min), but higher quiescent current (1.2 mA vs. 2.3 mA max). | Better suited for femtoampere-level sensor interfaces (e.g., ion-selective electrodes); less optimal for battery-constrained designs. | Select INA828IDR when ultra-low bias current dominates over power budget; verify layout compatibility with different pinout. |
| AD8422ARMZ | Same architecture and pinout, but BRM grade: 92 dB min CMRR (vs. 94 dB), 0.9 µV/°C max offset drift (vs. 0.2 µV/°C), wider temp range (−40°C to +125°C). | Acceptable for industrial control where extended temperature operation is prioritized over highest dc precision. | AD8422ARMZ offers drop-in replacement in MSOP-8 footprint; confirm system-level drift budget permits looser offset specification. |
Compared with INA828IDR and AD8422ARMZ, the AD8421BRZ provides the best balance of ultra-low noise, tight dc precision, and low power in SOIC-8 - making it optimal for portable medical devices and high-resolution data loggers where both accuracy and energy efficiency are critical.
Availability
AD8421BRZ is available at Aetrix Electronics and suitable for medical instrumentation, precision data acquisition, and vibration analysis requiring stable component supply across long production lifecycles and global regulatory compliance.
Supply support for AD8421BRZ 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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA, serving industrial, automotive, communications, and healthcare markets.
The AD8421 product line delivers low-noise, low-power instrumentation amplifiers optimized for precision sensor signal conditioning - targeting applications demanding high CMRR, low drift, and robust input protection in compact packages.
FAQ
What is the maximum gain achievable with AD8421BRZ?
The AD8421BRZ supports a gain range of 1 to 10,000 using a single external resistor connected between pins 2 and 3, calculated as G = 1 + (9.9 kΩ/RG). At G = 10,000, the required RG is 1 Ω, and bandwidth reduces to 200 kHz. The AD8421BRZ maintains usable performance across this full range while preserving 94 dB CMRR at unity gain.
Does AD8421BRZ support single-supply operation?
Yes, the AD8421BRZ operates from a single supply of 5 V to 36 V, as specified in its absolute maximum ratings and electrical characteristics. When used in single-supply mode, the input common-mode range extends from (−VS + 2.3 V) to (+VS − 1.8 V), and the reference pin allows output level shifting to accommodate unipolar ADC inputs.
What is the purpose of the REF pin on AD8421BRZ?
On the AD8421BRZ, the REF pin accepts a low-impedance voltage source to add a precise DC offset to the output without affecting gain accuracy. With 1 ppm/V reference gain error, it enables ratiometric zero-adjustment in bridge circuits and supports level-shifting for ADCs operating on different supply domains - a key feature confirmed in the AD8421BRZ datasheet Figure 1 and Table 6.
How does AD8421BRZ handle input overvoltage conditions?
The AD8421BRZ incorporates built-in input protection that allows voltages up to 40 V beyond the opposite supply rail (e.g., +IN can tolerate −VS + 40 V) without damage. This eliminates external protection components in harsh environments. The protection mechanism is detailed in the Absolute Maximum Ratings table and verified in Figures 15–18 of the AD8421BRZ datasheet.
What package type is used for AD8421BRZ?
The AD8421BRZ is supplied in an 8-lead SOIC (Small Outline Integrated Circuit) package with an exposed thermal pad. It is rated for operation from −40°C to +85°C and has a thermal resistance θJA of 107.8°C/W. Pin configuration matches standard SOIC-8 footprints, and the exposed pad may be connected to −VS for improved thermal performance.
AD8421BRZ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Amplifier Type:
- Instrumentation
- Number of Circuits:
- 1
- Output Type:
- -
- Slew Rate:
- 35V/µs
- Gain Bandwidth Product:
- -
- -3db Bandwidth:
- 10 MHz
- Current - Input Bias:
- 100 pA
- Voltage - Input Offset:
- 25 µV
- Current - Supply:
- 2mA
- Current - Output / Channel:
- 65 mA
- Voltage - Supply Span (Min):
- 5 V
- Voltage - Supply Span (Max):
- 36 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
AD8421BRZ FAQ
1.How can I place an order for AD8421BRZ through Aetrix?
Please submit a Request for Quotation (RFQ) for AD8421BRZ 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 AD8421BRZ reliable?
The price and inventory of AD8421BRZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD8421BRZ is usually 5 days.
3.What payment methods are accepted for AD8421BRZ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD8421BRZ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD8421BRZ?
AD8421BRZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD8421BRZ 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 AD8421BRZ?
For technical support, including AD8421BRZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD8421BRZ requirements.
6.How does Aetrix verify that AD8421BRZ is sourced from the original manufacturer or authorized distributors?
All AD8421BRZ 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 AD8421BRZ meets industry standards.
7.What is the process for return or replacement of AD8421BRZ?
All AD8421BRZ units undergo pre-shipment inspection (PSI). If there is an issue with AD8421BRZ, 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 AD8421BRZ part is unused and in its original packaging.
Return procedure for AD8421BRZ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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