AD8421BRZ

The AD8421 is a low cost, low power, ultralow noise, ultralow bias current, high speed instrumentation amplifier ideally suited for a wide range of signal conditioning and data acquisition applications. The device features an extremely high CMRR, enabling extraction of low level signals buried in high frequency common-mode noise over a wide temperature range. With a bandwidth of 10 MHz, slew rate of 35 V/μs, and 0.001% (G = 10) settling time of 0.6 μs, the AD8421 can amplify high speed signals and excels in applications requiring high channel count multiplexed systems. The current feedback architecture maintains high performance even at high gains. For example, at G = 100, the bandwidth is 2 MHz with a settling time of 0.8 μs. The AD8421 offers excellent distortion performance, making it suitable for demanding applications such as vibration analysis. The AD8421 provides 3 nV/√Hz input voltage noise and 200 fA/√Hz current noise with a quiescent current of only 2 mA, making it ideal for measuring low level signals. For applications with large source impedances, the AD8421 employs innovative process technology and design techniques to deliver noise performance limited only by the sensor. The AD8421 uses a unique protection scheme that ensures robust inputs while maintaining ultralow noise. This protection allows input voltages up to 40 V beyond the opposite supply rail without causing damage. Gain is set from 1 to 10,000 via a single resistor. The reference pin can be used to apply a precise offset to the output voltage. The AD8421 is rated for operation over the −40°C to +85°C temperature range, with typical performance curves guaranteed up to 125°C, and is available in 8-lead MSOP and SOIC packages.

Applications

• Medical instruments
• Precision data acquisition systems
• Microphone preamplifiers
• Vibration analysis
• Multiplexed input applications
• ADC drivers

Key features

• Low power consumption, maximum supply current 2.3 mA
• Low noise: maximum input voltage noise 3.2 nV/√Hz at 1 kHz, current noise 200 fA/√Hz at 1 kHz
• Excellent AC characteristics: bandwidth 10 MHz (G = 7), bandwidth 2 MHz (G = 100), 0.001% settling time 0.6 μs (G = 10), CMRR 80 dB (20 kHz, G = 7), slew rate 35 V/μs
• High precision DC performance (AD8421BRZ): CMRR 94 dB (min, G = 7), input offset voltage drift 0.2 μV/°C (max), maximum gain drift 1 ppm/°C (G = 1), input bias current 500 pA (max)
• Input overvoltage protection, exceeding supply rail by 40 V
• ±2.5 V to ±18 V dual supply (5 V to 36 V single supply)
• Gain set by single resistor (G = 7 to 10,000)