Features and Benefits
- Low power
- 2.3 mA maximum supply current
- Low noise
- 3.2 nV/√Hz maximum input voltage noise at 1 kHz
- 200 fA/√Hz current noise at 1 kHz
- Excellent ac specifications
- 10 MHz bandwidth (G = 1)
- 2 MHz bandwidth (G = 100)
- 0.6 µs settling time to 0.001% (G = 10)
- 80 dB CMRR to 20 kHz (G = 1)
- 35 V/µs slew rate
- High precision dc performance (AD8421BRZ)
- 94 dB CMRR minimum (G = 1)
- 0.2 μV/°C maximum input offset voltage drift
- 1 ppm/°C maximum gain drift (G = 1)
- 500 pA maximum input bias current
- Inputs protected to 40 V from opposite supply
- ±2.5 V to ±18 V dual supply (5 V to 36 V single supply)
- Gain set with a single resistor (G = 1 to 10,000)
- Available in 8-lead LFCSP, 8-lead MSOP, and 8-lead SOIC
- Download AD8421-KGD Data Sheet
- Available As Known Good Die and fully guaranteed to data sheet specifications
- Download AD8421-EP data sheet (pdf)
- Military temperature range (−55°C to +125°C)
- Controlled manufacturing baseline
- One assembly/test site
- One fabrication site
- Enhanced product change notification
- Qualification data available on request
- V62/13625 DSCC Drawing Number
The AD8421 is a low cost, low power, extremely low noise, ultralow bias current, high speed instrumentation amplifier that is ideally suited for a broad spectrum of signal conditioning and data acquisition applications. This product features extremely high CMRR, allowing it to extract low level signals in the presence of high frequency common-mode noise over a wide temperature range.
The 10 MHz bandwidth, 35 V/µs slew rate, and 0.6 µs settling time to 0.001% (G = 10) allow the AD8421 to amplify high speed signals and excel in applications that require high channel count, multiplexed systems. Even at higher gains, the current feedback architecture maintains high performance; for example, at G = 100, the bandwidth is 2 MHz and the settling time is 0.8 µs. The AD8421 has excellent distortion performance, making it suitable for use in demanding applications such as vibration analysis.
The AD8421 delivers industry-leading 3 nV/√Hz input voltage noise and 200 fA/√Hz current noise with only 2 mA quiescent current, making it an ideal choice for measuring low level signals. For applications with high source impedance, the AD8421 employs innovative process technology and design techniques to provide noise performance that is limited only by the sensor.
The AD8421 uses unique protection methods to ensure robust inputs while still maintaining very low noise. This protection allows input voltages up to 40 V from the opposite supply rail without damage to the part.
A single resistor sets gains between 1 and 10,000. The reference pin can be used to apply a precise offset to the output voltage.
The AD8421 performance is specified from −40°C to +85°C for the 8-lead MSOP and SOIC packages, and from −40°C to 125°C for the 8-lead LFCSP package.
- Medical instrumentation
- Precision data acquisition
- Microphone preamplification
- Vibration analysis
- Multiplexed input applications
- ADC driver
Product Lifecycle Recommended for New Designs
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
Evaluation Kits (1)
Analog Devices provides a line of evaluation boards designed to help users evaluate our instrumentation amplifiers in 8 pin packages. Access the user guide UG-261.
This user guide describes three generic evaluation boards that can be used to evaluate many of Analog Devices instrumentation amplifiers. For information on the performance of a specific instrumentation amplifier, see the data sheet for that instrumentation amplifier.
- 3 generic, easy-to-use evaluation boards
- Shipped with an assortment of Analog Devices in-amps
- Solder in the in-amp to be tested
- Test pins already populated
- Decoupling capacitors already populated
- EVAL-INAMP-62RZ board: Compatible with AD620, AD621, AD622, AD623, AD627, AD8223, AD8225, LT1167, LT1168 and LT6370 in SOIC or PDIP
- EVAL-INAMP-82RZ board: Compatible with AD8221, AD8226, AD8227, AD8228, AD8229, AD8421, AD8428, and AD8429 in SOIC package
- EVAL-INAMP-82RMZ board: Compatible with AD8220, AD8221, AD8226, AD8227, AD8228, AD8236, and AD8421 in MSOP package
Tools & Simulations
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
Models for the following parts are available in LTspice:
In-Amp Diamond Plot Tool
The Diamond Plot Tool is a web application that generates a configuration-specific Output Voltage Range vs. Input Common-Mode Voltage graph, also known as the Diamond Plot, for Analog Devices Instrumentation Amplifiers. Based on user inputs such as supply voltage, gain, and input signal range, the tool detects saturation and recommends in-amps for which the input signal is in-range and the configuration is valid. Avoid saturation, find the best in-amp for your design, and save time.
StudentZone Articles (1)
Rarely Asked Questions (2)
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.