Description

AD8421 Universal Instrumentation Amplifier Module Lower Power Consumption Dual Power Supply Mode

Description:
The AD8421 is a low cost, low power, extremely low noise, ultra low 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 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 the gain from 1 to 10,000. The reference pin can be used to apply a precise offset to the output voltage. The AD8421 is specified from −40℃ to +85℃and has typical performance curves to 125℃. It is available in 8-lead MSOP and SOIC packages.

Features:
● 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 at 20 kHz (G = 1)
   - 35 V/μs slew rate
● High precision DC performance (AD8421BRZ)
   - 94 dB CMRR minimum (G = 1)
   - 0.2 μV/℃ maximum input offset voltage drift
   - 1 ppm/℃ 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)

Applications:
- Medical instrumentation
- Precision data acquisition
- Microphone preamplification
- Vibration analysis
- Multiplexed input applications
- ADC driver

Module Schematic Diagram:


When its input voltage is provided by single power supply, it needs negative voltage module converter. The product comes with J5 diconnected, J10, J11, J8 and J6 connected.

When its input voltage is provided by dual power supply, the product comes with J7 and J11 diconnected, J10, J8 and J7 connected.

1. For Single Power Supply Mode:
When its input signals (IN- and IN+) are in the range of 0~VCC for positive supply (differential signal with DC offset), the module requires single power supply. Please not connect J10 and J11. Just connect J7, J8 and J6. Now it is powered by single power supply, DC offset voltage can be input via SMA3 (or J4) ports. Or just connect J6 and set its bias voltage via a potentiometer.

2. For Dual Power Supply Mode:
When its input signals (IN- and IN+) are mixed with negative voltage or pure AC signals, the module needs dual power supply. Please disconnect J7. Just connect J8, J10 and J11. Now it is powered by dual power supply, DC offset voltage can be input via SMA3 (or J4) ports. Or just connect J7 and set its bias voltage via a potentiometer.

Output Signal Vout=[(Vin+)-(Vin-)]*G+Vref

G = 1 + (9.9 kΩ/RG)

Package Included:
- 1 x Instrumentation Amplifier Module Dual Power Supply Mode