AD8639ARMZ

The AD8638/AD8639 are single and dual wide bandwidth, auto-zero amplifiers featuring rail-to-rail output swing and low noise.

These amplifiers have very low offset, drift, and bias current. Operation is fully specified from 5 V to 16 V single supply (±2.5 V to ±8 V dual supply).

The AD8638/AD8639 provide benefits previously found only in expensive zero-drift or chopper-stabilized amplifiers. Using the Analog Devices, Inc., topology, these auto-zero amplifiers combine low cost with high accuracy and low noise. No external capacitors are required. In addition, the AD8638/AD8639 greatly reduce the digital switching noise found in most chopper- stabilized amplifiers.

With a typical offset voltage of only 3 μV, drift of 0.01 μV/°C, and noise of 1.2 μV p-p (0.1 Hz to 10 Hz), the AD8638/AD8639 are suited for applications in which error sources cannot be tolerated. Position and pressure sensors, medical equipment, and strain gage amplifiers benefit greatly from nearly zero drift over their operating temperature ranges. Many systems can take advantage of the rail-to-rail output swing provided by the AD8638/AD8639 to maximize signal-to-noise ratio (SNR).

The AD8638/AD8639 are specified for the extended industrial temperature range (−40°C to +125°C). The single AD8638 is available in tiny 5-lead SOT-23 and 8-lead SOIC packages. The dual AD8639 is available in 8-lead MSOP, 8-lead SOIC, and 8-lead LFCSP packages.

The AD8638/AD8639 are members of a growing series of auto- zero op amps offered by Analog Devices (see Table 1 in the data sheet).

Key Features and Benefits

• •  Low Offset Voltage: 9 μV maximum
• •  Offset drift: 0.04 μV/°C maximum
• •  Rail-to-Rail output swing
• •  5 V to 16 V single-supply or ±2.5 V to ±8 V dual-supply operation
• •  High gain: 136 dB typical
• •  High CMRR: 133 dB typical
• •  High PSRR: 143 dB typical
• •  Very low input bias current: 40 pA maximum
• •  Low supply current: 1.3 mA maximum

Applications

• •  Pressure and position sensors
• •  Strain gage amplifiers Medical instrumentation
• •  Thermocouple amplifiers Automotive sensors
• •  Precision references
• •  Precision current sensing

Evaluation Board

The AD8639 can be evaluated with the EVAL-OPAMP-2

Block Diagrams and Tables

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