Ultra-Low Offset/Drift, Precision Instrumentation Amplifiers with REF Buffer

 

Part Number	Replacement	Explanation

Description

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The MAX4208/MAX4209 ultra-low offset and drift instrumentation amplifiers feature exceptional precision specifications, low power consumption, rail-to-rail output, excellent gain-bandwidth product, and buffered REFIN/MODE input in a very small µMAX® package. These devices use a spread-spectrum, autozeroing technique that constantly measures and corrects the input offset, eliminating drift over time and temperature and the effect of 1/f noise. This technique achieves less than 20µV offset voltage, allows ground-sensing capability, provides ultra-low CMOS input bias current and increased common-mode rejection performance.

The MAX4208/MAX4209 provide high-impedance inputs optimized for small-signal differential voltages (±100mV). All devices provide a gain-bandwidth product of 750kHz.

The MAX4208 provides an adjustable gain with two external resistors or unity gain with FB connected to OUT. The MAX4209 is available with a fixed gain of 100V/V with ±0.03% (typ) accuracy. Both devices include a reference input (REF) to level-shift the output, allowing for bipolar signals in single-supply applications. In both devices, REFIN/MODE is an input to a precision unity-gain buffer, which sets the REF voltage to level-shift the output. The internal REF buffer allows the reference to be set by a simple resistive divider or an ADC reference without any loading error.

The MAX4208/MAX4209 operate with a 2.85V to 5.5V single-supply voltage and consume only 750µA of quiescent current (when the internal buffer is off) and only 1.4µA in shutdown mode. These amplifiers also operate with ±2.5V dual supplies with REF connected to ground and REFIN/MODE to V_SS. The MAX4208/MAX4209 are available in space-saving 8-pin µMAX packages and are specified over the automotive operating temperature range (-40°C to +125°C).

MAX4208, MAX4209: Typical Application Circuit Enlarge+

Key Features

• Spread-Spectrum, Auto-Zero Instrumentation Amplifiers Improve DC Characteristics to Maximize Sensor Performance
  • Input Offset Voltage: ±20µV (max) at +25°C
  • ±0.25% (max) Gain Error
  • Low 0.2µV/°C Offset Voltage Drift
  • 1pA CMOS Input Bias Current
  • True Ground Sensing with Rail-to-Rail Output
  • 750kHz Gain-Bandwidth Product
• Buffered REF Input for High Accuracy and Bipolar Operation
• Low Power Operation Supports Remote Sensing and Battery-Powered Applications
  • 2.85V to 5.5V Single-Supply Operation (or ±1.425V to ±2.75V Dual Supplies)
  • 750µA Supply Current
  • 1.4µA Shutdown Mode
• Adjustable (MAX4208) and Fixed Gain of 100 (MAX4209) Provide Design Flexibility

Applications/Uses

• Battery-Powered Medical Equipment
• Differential Voltage Amplification
• Industrial Process Control
• Notebook Computers
• Precision Low-Side Current Sense
• Strain-Gauge Amplifiers