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

Instrumentation Amplifiers Use Autozero to Achieve 20µV (max) Offset

Product Details

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 VSS. 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).

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
Parametric specs for Instrumentation/Difference Amplifiers
Architecture Indirect Current-Feedback
# Amplifiers 1
VCMVR (to Neg. Rail) Yes
Rail to Rail Output Only
AV (V/V) 10
100
1000
ICC per Amp. (mA) (typ) 0.75
VOS (µV) (max) 20
CMRR @DC (dB) (typ) 135
PSRR @DC (dB) (typ) 125
Input IBIAS (nA) (max) 0.01
Unity Gain BW (MHz) (typ) 0.75
Oper. Temp. (°C) -40 to +125
Package/Pins UMAX/8
Budgetary
Price (See Notes)
$1.70 @1k
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Simplified Block Diagram

MAX4208, MAX4209: Typical Application Circuit MAX4208, MAX4209: Application Circuit Zoom icon

Design & Development

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Additional Resources

The Beauty of Precision Op Amps

Description

The MAX4208 evaluation kit (EV kit) simplifies evaluation of the MAX4208 ultra-low offset/drift, adjustable gain, precision instrumentation amplifier in a µMAX® package. The MAX4208 features high-impedance differential inputs optimized for small voltages (±100mV max) and provides rail-to-rail output. The MAX4208 EV kit is configured for a gain of 148V/V. The EV kit operates from a single-supply voltage between 2.85V and 5.5V, or dual supplies providing ±1.425V to ±2.75V.

The MAX4208 EV kit can also be used to evaluate the MAX4209 fixed-gain amplifiers. The MAX4208 IC temperature range is -40°C to +125°C.

The MAX4209 EV kit, available separately, evaluates the 100V/V fixed-gain MAX4209 amplifier without external gain-setting resistors.

Note: To evaluate a MAX4209 IC featuring internal gain-setting resistors, order a MAX4209EVKIT+ or request a free sample of the MAX4209 IC along with the MAX4208EVKIT+. See the Part Selection Table in the full data sheet for IC ordering information.

View Details

Features

  • Single- or Dual-Supply Operation
    • 2.85V to 5.5V Single-Supply Operation
    • ±1.425V to ±2.75V Dual-Supply Operation
  • Adjustable Voltage Gain Configured to 148V/V
  • Rail-to-Rail Output
  • Configurable Reference Voltage: Externally or Internally Buffered
  • Optional Current-Sense Mode
  • Fully Assembled and Tested

Description

The MAX4209 evaluation kit (EV kit) simplifies evaluation of the MAX4208 ultra-low offset/drift, fixed gain, precision instrumentation amplifier in a µMAX® package. The MAX4209 features high-impedance differential inputs optimized for small voltages (±100mV max) and provides rail-to-rail output. The MAX4209 EV kit circuit uses the 100V/V fixed-voltage-gain version of the MAX4209. The EV kit operates from a single-supply voltage between 2.85V and 5.5V, or dual supplies providing ±1.425V to ±2.75V.

The MAX4209 EV kit can also evaluate the 10V/V and 1000V/V fixed-gain versions of the MAX4209 amplifiers, as well as the MAX4208 adjustable-gain amplifier. The MAX4209 IC temperature range is -40°C to +125°C.

The MAX4208 EV kit, available separately, evaluates the MAX4208 adjustable-gain amplifier with external gain-setting resistors.

Note: To evaluate a MAX4208 IC featuring externally adjustable gain, order a MAX4208EVKIT+ or request a free sample of the MAX4208AUA+ IC along with the MAX4209EVKIT+. For the alternate-gain versions of the MAX4209 IC, see the Part Selection Table in the full data sheet for IC ordering information.

View Details

Features

  • Single- or Dual-Supply Operation
    • 2.85V to 5.5V Single-Supply Operation
    • ±1.425V to ±2.75V Dual-Supply Operation
  • 100V/V Fixed Voltage Gain
  • Rail-to-Rail Output
  • Configurable Reference Voltage: Externally or Internally Buffered
  • Optional Current-Sense Mode
  • Fully Assembled and Tested

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SIMULATION MODELS

MAX4209 Orcad Library

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Parameters

Parametric specs for Instrumentation/Difference Amplifiers
Architecture Indirect Current-Feedback
# Amplifiers 1
VCMVR (to Neg. Rail) Yes
Rail to Rail Output Only
AV (V/V) 10
100
1000
ICC per Amp. (mA) (typ) 0.75
VOS (µV) (max) 20
CMRR @DC (dB) (typ) 135
PSRR @DC (dB) (typ) 125
Input IBIAS (nA) (max) 0.01
Unity Gain BW (MHz) (typ) 0.75
Oper. Temp. (°C) -40 to +125
Package/Pins UMAX/8
Budgetary
Price (See Notes)
$1.70 @1k

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

Description

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 VSS. 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).

Simplified Block Diagram

MAX4208, MAX4209: Typical Application Circuit MAX4208, MAX4209: Application Circuit Zoom icon

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal.