AD8421ARZ - 3nV/√Hz Low Power In-Amp | Analog Devices
料号： AD8421ARZ ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $5.29 | $5.29 |
| 10 | $4.76 | $47.60 |
| 100 | $4.23 | $423.00 |
| 500 | $3.81 | $1,905.00 |
| 1,000 | $3.39 | $3,390.00 |
AD8421ARZ 概述
An instrumentation amplifier (in-amp) is a type of differential amplifier that has high input impedance and high common-mode rejection, making it ideal for measuring small signals in the presence of large common-mode voltages. It is a key building block in precision analog front ends, often used to amplify signals from sensors such as strain gauges, thermocouples, and medical electrodes. The AD8421 belongs to the family of precision instrumentation amplifiers, which are essential in applications requiring accurate, low-noise signal conditioning.
Key features of the AD8421ARZ include its extremely low noise of 3 nV/√Hz, which is critical for high-resolution measurement systems, and its ultralow bias current, which minimizes errors when interfacing with high-impedance sources. The high speed of 10 MHz bandwidth and 35 V/µs slew rate allows it to capture fast transients, making it suitable for high-speed data acquisition. The device also features a reference pin for precise output offsetting, and it operates from a single or dual supply, providing design flexibility.
Technically, the AD8421 uses a three-op-amp topology with laser-trimmed resistors to achieve high accuracy and stability. The input stage provides high common-mode rejection, while the output stage drives the load. The device is designed for low power consumption, making it suitable for battery-powered and portable applications. The SOIC package is widely used and easy to integrate into PCB designs.
Typical applications include medical instrumentation, such as ECG and EEG monitoring, where low noise and high CMRR are essential. It is also used in industrial process control, precision data acquisition systems, and transducer interfaces. The AD8421's combination of low noise, low power, and high speed makes it a versatile choice for many precision analog applications.
When designing with the AD8421, ensure proper supply decoupling with 0.1 µF capacitors close to the supply pins. The reference pin can be used to level-shift the output, which is useful in single-supply applications. Also, consider the input common-mode range to avoid saturation.
直接替换替代料： AD8421ARZ ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
本系列中的变体
可与以下型号直接替换的同系列型号： AD8421ARZ （相同外形与封装尺寸） ——差异在于 Package, Gain Range, Slew Rate, Amplifier Type, Input Offset Voltage.
快速对比工具——选择替代料号进行并排对比：
AD8421BRZ
✅ 直接替换✓ 有现货
$4.9 / 个
查看数据手册 →AD8421ARZ-R7
✅ 直接替换📋 参考替代料（不在目录中）
AD8421ARZ-RL
✅ 直接替换📋 参考替代料（不在目录中）
AD8221ARZ
✅ 直接替换 ⚠️ 规格未核验✓ 有现货
$3.29 / 个
查看数据手册 →INA128
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
AD8421ARZ 最大额定值与电气特性
| Amplifier Type | Instrumentation Amplifier |
| Number of Circuits | 1 |
| Input Offset Voltage | 60 µV |
| Slew Rate | 35 V/µs |
| Bandwidth | 10 MHz |
| Supply Voltage Range | 5 V to 36 V |
| Voltage Noise Density | 3 nV/√Hz |
| 工作温度范围 | -40°C to +85°C |
| 封装 | 8-SOIC |
| 安装类型 | Surface Mount |
| RoHS 状态 | Compliant |
| Reference Pin | Yes |
AD8421ARZ 引脚配置
| 引脚 1 | -IN — Inverting input |
| 引脚 2 | RG — Gain setting resistor |
| 引脚 3 | RG — Gain setting resistor |
| 引脚 4 | -VS — Negative supply |
| 引脚 5 | REF — Reference voltage for output offset |
| 引脚 6 | OUT — Output |
| 引脚 7 | +VS — Positive supply |
| 引脚 8 | +IN — Non-inverting input |
典型应用
AD8421ARZ 适用于 6 应用s: Medical Instrumentation, Industrial Process Control, Data Acquisition Systems, Transducer Interfaces, Battery-Powered Instruments, High-Speed Signal Conditioning.
Medical Instrumentation
The AD8421ARZ is ideal for medical instrumentation such as ECG and EEG due to its low noise (3 nV/√Hz) and high CMRR. It amplifies small biopotential signals while rejecting common-mode interference from the body and power lines. Its low bias current minimizes loading on high-impedance electrodes, and its wide supply range (5V to 36V) accommodates battery or mains-powered designs. The high bandwidth (10 MHz) ensures faithful reproduction of fast signal transients, while the reference pin allows precise output level shifting for single-supply operation.
推荐
Industrial Process Control
In industrial process control, the AD8421ARZ provides accurate signal conditioning for sensors like strain gauges and pressure transducers. Its low offset voltage (60 µV) and low noise ensure precise measurement of small signals in noisy industrial environments. The high common-mode rejection rejects interference from motors and power lines, while the wide supply range (up to 36V) allows direct operation from industrial 24V rails. The 10 MHz bandwidth supports fast control loops, and the low power consumption reduces heat in enclosures. The SOIC package is easy to integrate into existing PCB designs.
推荐
Data Acquisition Systems
The AD8421ARZ is well-suited for data acquisition systems requiring high-speed, low-noise signal conditioning. Its 10 MHz bandwidth and 35 V/µs slew rate allow it to accurately amplify fast transients, making it ideal for digitizing dynamic signals. The low noise (3 nV/√Hz) preserves signal integrity, and the low bias current minimizes errors when interfacing with high-impedance sources. The reference pin enables precise offset adjustment, which is useful for bipolar-to-unipolar conversion. The device operates from 5V to 36V, making it compatible with a wide range of ADC supplies.
推荐
Transducer Interfaces
The AD8421ARZ is an excellent choice for transducer interfaces, such as thermocouple and RTD signal conditioning. Its ultralow bias current minimizes errors from high-impedance sources, and its low noise (3 nV/√Hz) ensures accurate temperature measurement. The high common-mode rejection rejects interference from power lines and motors, while the wide supply range (5V to 36V) allows operation from various power rails. The 10 MHz bandwidth is more than sufficient for temperature sensing, and the low power consumption is beneficial for portable instruments. The reference pin allows easy offset calibration.
推荐
Battery-Powered Instruments
The AD8421ARZ is ideal for battery-powered instruments due to its low power consumption and wide supply range (5V to 36V). It can operate directly from a 9V battery or a 3.3V supply with proper configuration. The low noise (3 nV/√Hz) ensures accurate measurements, and the low bias current extends battery life by minimizing current draw from sensors. The 10 MHz bandwidth supports fast sampling, while the SOIC package is compact and lightweight. The reference pin allows output level shifting for single-supply operation, making it easy to interface with ADCs.
推荐
High-Speed Signal Conditioning
The AD8421ARZ is designed for high-speed signal conditioning applications, such as vibration analysis and high-frequency sensor interfaces. Its 10 MHz bandwidth and 35 V/µs slew rate allow it to amplify fast transients without distortion. The low noise (3 nV/√Hz) preserves signal fidelity, and the high common-mode rejection rejects interference in noisy environments. The device operates from 5V to 36V, making it suitable for a variety of supply rails. The SOIC package is easy to integrate into high-speed PCB layouts, and the reference pin allows precise offset control.
推荐
推荐产品汇总
工程参考数据： AD8421ARZ ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | AD8421BRZ | AD8221ARZ | INA128 |
|---|---|---|---|---|
| Package | 8-SOIC | 8-SOIC | 8-SOIC | 8-SOIC |
| Brand | Analog Devices | Analog Devices | Analog Devices | Texas Instruments |
| Voltage Noise Density | 3 nV/√Hz | 3 nV/√Hz | 8 nV/√Hz | 8 nV/√Hz |
| Bandwidth | 10 MHz | 10 MHz | 1 MHz | 200 kHz |
| Slew Rate | 35 V/µs | 35 V/µs | 2 V/µs | 0.4 V/µs |
| Input Offset Voltage | 60 µV | 25 µV (max) | 60 µV | 50 µV |
| Supply Voltage Range | 5V to 36V | 5V to 36V | 4.5V to 36V | 4.5V to 36V |
| Price (1pc) | $5.29 | $6.50 | $4.50 | $3.80 |
关键差异点
- Lowest noise in its class （对比 AD8221ARZ)
- Higher bandwidth （对比 INA128)
- Higher slew rate （对比 AD8221ARZ)
设计说明
Ensure proper supply decoupling with 0.1 µF ceramic capacitors placed close to the +VS and -VS pins. For high-frequency noise, add a 10 µF tantalum capacitor in parallel. The AD8421 operates from 5V to 36V, so verify the supply voltage does not exceed the absolute maximum ratings. Use a low-noise supply to maintain the amplifier's low noise performance.
For optimal noise performance, keep the input traces short and shielded. Use a ground plane under the amplifier to reduce noise pickup. The gain-setting resistors (RG) should be placed close to the RG pins to minimize parasitic capacitance. For high-speed applications, use a 4-layer PCB with dedicated power and ground planes.
Do not exceed the input common-mode voltage range, as this can cause output saturation. The reference pin (REF) can be used to level-shift the output, but ensure it is driven by a low-impedance source. For single-supply operation, set the REF pin to mid-supply to maximize output swing. Also, avoid using high-value gain resistors, as they can increase noise and offset errors.
合规信息
RoHS compliant per Analog Devices product page. Not AEC-Q100 qualified. Lead-free per SOIC package.
