The AD8420 is a micropower, low-cost instrumentation amplifier designed for precision amplification of small differential signals in the presence of large common-mode voltages.
Function: Wide Supply Range, Micropower, Rail-to-Rail Instrumentation Amplifier
Package: 8-lead MSOP type
Manufacturer: Analog Devices
Pinouts:
Description
The AD8420 is a low cost, micropower, wide supply range, instrumentation amplifier with a rail-to-rail output and a novel architecture that allows for extremely flexible design. It is optimized to amplify small differential voltages in the presence of large common-mode signals. The AD8420 is based on an indirect current feedback architecturethat gives it an excellent input common-mode range. Unlike conventional instrumentation amplifiers, the AD8420can easily amplify signals at or even slightly below ground without requiring dual supplies. The AD8420 has rail-to-rail output, and the output voltage swing is completely independent of the input common mode voltage.
It utilizes an indirect current feedback architecture, enabling a wide input common-mode range and allowing operation even when input signals are at or slightly below ground on a single supply. With rail-to-rail output and very low power consumption, it is well suited for battery-powered and high-accuracy sensing applications.
Features
- Micropower operation with maximum supply current of 80µA
- High common-mode rejection ratio (CMRR ≥ 100 dB)
- Rail-to-rail output swing
- Wide input voltage range, including below ground capability
- Gain set using two external resistors
- Low gain drift across all gain settings
- Wide supply voltage range:
- Single supply: 2.7V to 36V
- Dual supply: ±2.7V to ±18V
- Bandwidth: 2.5 kHz at gain of 100
- Low input voltage noise: 55 nV/√Hz
- High DC precision with low offset voltage (max 125µV)
- Low offset drift (max 1µV/°C)
- Capable of driving capacitive loads up to ~700 pF
Design Notes
- Indirect current feedback architecture provides extended input common-mode range
- Can handle input signals near or below ground without requiring negative supply
- Gain is externally configurable, enabling flexible system design
- Low quiescent current makes it ideal for battery-powered applications
- Careful PCB layout is required to maintain high CMRR and low noise performance
- Capable of directly driving ADC inputs due to rail-to-rail output
How to Choose This Part
- Select for low-power precision measurement systems
- Ensure bandwidth meets application requirements at desired gain
- Evaluate noise performance for low-level signal amplification
- Confirm supply voltage compatibility with system design
- Consider alternative instrumentation amplifiers for higher bandwidth needs
Applications
- Bridge amplifiers
- Pressure measurement systems
- Medical instrumentation
- Portable data acquisition
- Multichannel sensing systems
Alternative / Equivalent Products
- AD623 – Low-cost instrumentation amplifier
- INA333 – Texas Instruments micropower INA
- AD8226 – Precision instrumentation amplifier
- INA126 – General-purpose instrumentation amplifier
- AD620 – Widely used instrumentation amplifier
Other data sheets are available within the file:
AD8420ARMZ, AD8420ARMZ-R7, AD8420ARMZ-RL
AD8420 Datasheet PDF Download
