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Analog Devices Inc. AD8421BRZ-R7
- Part No.:
- AD8421BRZ-R7
- Manufacturer:
- Analog Devices Inc.
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
AD8421BRZ-R7.pdf
- Description:
- IC INST AMP 1 CIRCUIT 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:6,430
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Product details
Overview
AD8421BRZ-R7 from Analog Devices is a low-power, ultra-low-noise instrumentation amplifier with 3.2 nV/√Hz input voltage noise, 2.3 mA supply current, and 10 MHz bandwidth at G = 1. It serves as a precision front-end signal conditioner for high-impedance sensors in medical instrumentation and vibration analysis systems.
For engineers reviewing the AD8421BRZ-R7 datasheet, AD8421BRZ-R7 pinout, AD8421BRZ-R7 application, or AD8421BRZ-R7 equivalent, key selection criteria include input bias current (≤0.5 nA), CMRR (≥94 dB at DC), gain-setting flexibility (G = 1–10,000 via single resistor), and ±2.5 V to ±18 V dual-supply operation.
Technical Context
The AD8421BRZ-R7 employs a current-feedback architecture that maintains 2 MHz bandwidth and 0.8 µs settling time to 0.001% at G = 100, 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.
Gain is set by a single external resistor across RG pins (G = 1 + 9.9 kΩ/RG), while the REF pin supports precise output offset adjustment. Input impedance is 30 GΩ || 3 pF differential and common-mode, supporting microvolt-level signal extraction from high-Z sources.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Noise | 3.2 nV/√Hz at 1 kHz - enables resolution of sub-µV signals in low-frequency sensor applications |
| Supply Current | 2.3 mA max - supports battery-powered portable instrumentation with minimal thermal load |
| CMRR (G = 1) | 94 dB min (DC–60 Hz) - rejects interference from 50/60 Hz mains and switching power supplies |
| Bandwidth (G = 1) | 10 MHz - accommodates fast transients in vibration analysis and ADC driver stages |
| Input Bias Current | 0.5 nA max - preserves signal integrity with >1 MΩ source impedances |
| Gain Range | 1 to 10,000 - configured with one external resistor, simplifying BOM and layout |
| Operating Supply | ±2.5 V to ±18 V dual or 5 V to 36 V single - interoperable with industrial and medical power rails |
Pinout & Package
AD8421BRZ-R7 is housed in an 8-lead SOIC package (body size 4.9 mm × 3.9 mm, 1.27 mm pitch). The exposed pad is unconnected per datasheet Figure 3.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (−IN) | Negative input terminal | Differential input node; accepts signals up to ±40 V beyond opposite supply rail |
| 2, 3 (RG) | Gain-setting terminals | Resistor connection points defining gain as G = 1 + 9.9 kΩ/RG |
| 4 (+IN) | Positive input terminal | Differential input node; matched to −IN for optimal CMRR |
| 5 (−VS) | Negative power supply | Reference for internal circuitry; exposed pad may be tied to this pin |
| 6 (REF) | Reference voltage input | Low-impedance level-shift node; gain to output is 1 ± 0.0001 V/V |
| 7 (VOUT) | Amplified output | Capable of ±Vs − 1.6 V swing into 2 kΩ load at 25°C |
| 8 (+VS) | Positive power supply | Supplies core amplifier and input stage; supports rail-to-rail reference input |
Key Features
| Feature | Design Value |
|---|---|
| Input Overvoltage Protection | ±40 V tolerance relative to opposite supply rail - eliminates need for external clamping diodes in harsh EMI environments |
| Ultra-Low Input Current Noise | 200 fA/√Hz at 1 kHz - minimizes Johnson noise contribution from high-source-impedance sensors |
| Single-Resistor Gain Setting | G = 1 + 9.9 kΩ/RG - reduces component count and layout sensitivity vs. multi-resistor networks |
| Wide Temperature Range | Specified from −40°C to +85°C - ensures performance stability in industrial and automotive under-hood applications |
| High-Speed Settling | 0.6 µs to 0.001% at G = 10 - supports high-throughput multiplexed DAQ systems with minimal dead time |
Applications
| Medical Instrumentation | Precision Data Acquisition |
|---|---|
Use Scenario: Extracting low-amplitude biopotential signals (e.g., ECG, EEG) from high-impedance dry electrodes in portable monitors. IC Role / Device Role / Timing Role: Front-end instrumentation amplifier providing differential gain, common-mode rejection, and DC-coupled signal conditioning. Use Value: 3.2 nV/√Hz noise floor and 94 dB CMRR enable detection of microvolt-level neural activity amid 50/60 Hz interference. | Use Scenario: Signal conditioning for 16-bit SAR ADCs in automated test equipment with multiplexed sensor inputs. IC Role / Device Role / Timing Role: High-speed, low-drift gain stage driving AD7685 with 0.6 µs settling to 0.001%. Use Value: 10 MHz bandwidth and 35 V/µs slew rate prevent distortion during fast step transitions between channels. |
| Vibration Analysis | Microphone Preamplification |
Use Scenario: Conditioning outputs from piezoelectric accelerometers in predictive maintenance systems monitoring rotating machinery. IC Role / Device Role / Timing Role: Low-noise, high-bandwidth amplifier preserving wide dynamic range and harmonic content up to 2 MHz at G = 100. Use Value: 2 MHz bandwidth at G = 100 and <0.01% THD support accurate FFT-based spectral analysis of mechanical resonance peaks. | Use Scenario: Pre-amplifying condenser microphone outputs in studio-grade audio interfaces with minimal added noise. IC Role / Device Role / Timing Role: Ultra-low-noise, high-input-impedance gain block interfacing electret or MEMS microphones to ADCs. Use Value: 30 GΩ || 3 pF input impedance prevents loading of high-Z microphone capsules; 3.2 nV/√Hz dominates system noise floor. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar instrumentation amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD8420ARMZ | Lower quiescent current (1.2 mA), same noise (3.2 nV/√Hz), but reduced CMRR (86 dB min) and bandwidth (3 MHz at G = 1) | Better suited for ultra-low-power battery-operated devices where 10 MHz bandwidth is unnecessary | Select AD8420ARMZ when supply current is critical and system bandwidth ≤3 MHz suffices |
| INA163UA | Higher noise (4.5 nV/√Hz), higher supply current (3.6 mA), but superior PSRR (120 dB) and wider gain range (1–1000) | Preferred in high-EMI industrial settings where power supply ripple rejection outweighs noise priority | Choose INA163UA when rejecting switching regulator noise is more critical than minimizing sensor-referred noise |
Compared with AD8421BRZ-R7, AD8420ARMZ trades bandwidth and CMRR for lower power, while INA163UA prioritizes PSRR over noise-making AD8421BRZ-R7 optimal for high-fidelity, wideband sensor signal chains demanding both ultra-low noise and high speed.
Availability
AD8421BRZ-R7 is available at Aetrix Electronics and suitable for medical instrumentation, precision data acquisition, and vibration analysis requiring stable component supply and long-term manufacturability.
Supply support for AD8421BRZ-R7 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, serving industrial, communications, automotive, and healthcare markets.
The AD8421 product line delivers low-noise, low-power instrumentation amplifiers optimized for extracting weak sensor signals in electrically noisy environments-targeting medical diagnostics, structural health monitoring, and precision test equipment.
FAQ
What is the maximum gain achievable with AD8421BRZ-R7?
The AD8421BRZ-R7 supports a gain range of 1 to 10,000, set by a single external resistor using the formula G = 1 + (9.9 kΩ/RG). At G = 10,000, RG = 0.99 Ω, requiring careful layout and low-tolerance resistor selection. Performance specifications such as bandwidth (0.2 MHz) and settling time (6 µs to 0.001%) are specified at this maximum gain in the AD8421BRZ-R7 datasheet.
Does AD8421BRZ-R7 support single-supply operation?
Yes, AD8421BRZ-R7 operates from a single supply of 5 V to 36 V, as confirmed in the Absolute Maximum Ratings and Specifications tables. When used in single-supply mode, the input common-mode range extends from −VS + 2.3 V to +VS − 1.8 V, and the REF pin allows output level-shifting to accommodate unipolar ADC inputs. The AD8421BRZ-R7 maintains full functionality-including 3.2 nV/√Hz noise and 2.3 mA supply current-across this range.
What is the purpose of the REF pin on AD8421BRZ-R7?
The REF pin on AD8421BRZ-R7 provides a precision level-shift capability: applying a voltage to REF adds that voltage directly to the output (gain = 1 ± 0.0001 V/V). This enables bipolar-to-unipolar conversion for ADC interfacing, offset trimming without affecting gain accuracy, and rejection of common-mode drift in multi-stage systems. The REF input has 20 kΩ resistance and accepts voltages from −VS to +VS, as specified for AD8421BRZ-R7.
How does AD8421BRZ-R7 handle input overvoltage conditions?
AD8421BRZ-R7 incorporates robust input protection allowing input voltages up to −VS + 40 V or +VS − 40 V without damage-exceeding typical op-amp limits by >2×. This is achieved through internal series resistance and clamp structures that limit input current to safe levels (<1 mA) even during sustained overvoltage. The AD8421BRZ-R7 datasheet confirms this behavior in Figures 15–18 and Absolute Maximum Ratings Table 4.
Is AD8421BRZ-R7 pin-compatible with other members of the AD8421 family?
Yes, AD8421BRZ-R7 shares identical pinout and footprint with all AD8421 variants-including AD8421ARZ, AD8421ARMZ, and AD8421ACPZ-in the 8-lead SOIC, MSOP, and LFCSP packages. Pin functions (−IN, RG, +IN, −VS, REF, VOUT, +VS) and electrical behavior are consistent across grades; only performance specifications (e.g., CMRR, offset drift) differ. This allows direct substitution in existing layouts when upgrading to the BR grade's 94 dB CMRR minimum.
AD8421BRZ-R7 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- 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-R7 FAQ
1.How can I place an order for AD8421BRZ-R7 through Aetrix?
Please submit a Request for Quotation (RFQ) for AD8421BRZ-R7 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-R7 reliable?
The price and inventory of AD8421BRZ-R7 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD8421BRZ-R7 is usually 5 days.
3.What payment methods are accepted for AD8421BRZ-R7?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD8421BRZ-R7 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD8421BRZ-R7?
AD8421BRZ-R7 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD8421BRZ-R7 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-R7?
For technical support, including AD8421BRZ-R7 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD8421BRZ-R7 requirements.
6.How does Aetrix verify that AD8421BRZ-R7 is sourced from the original manufacturer or authorized distributors?
All AD8421BRZ-R7 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-R7 meets industry standards.
7.What is the process for return or replacement of AD8421BRZ-R7?
All AD8421BRZ-R7 units undergo pre-shipment inspection (PSI). If there is an issue with AD8421BRZ-R7, 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-R7 part is unused and in its original packaging.
Return procedure for AD8421BRZ-R7:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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