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Amplifier and Data Converter Selection Guide

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30<br />

<strong>Amplifier</strong>s<br />

➔<br />

Instrumentation <strong>Amplifier</strong>s<br />

Single-Supply, RRIO, Low-Offset, Low-Drift Instrumentation <strong>Amplifier</strong>s<br />

INA326, INA327 (Shutdown Version)<br />

Get samples, datasheets <strong>and</strong> app reports at: www.ti.com/sc/device/INA326 <strong>and</strong> www.ti.com/sc/device/INA327<br />

Key Features<br />

• Low offset: 100µV (max)<br />

• Low offset drift: 0.4µV/°C (max)<br />

• Excellent long-term stability<br />

• Very-low 1/f noise<br />

• True rail-to-rail I/O<br />

• Input common-mode range:<br />

• 20mV below negative rail<br />

• 100mV above positive rail<br />

• Wide output swing: within 10mV of rails<br />

• Single supply range: +2.7V to +5.5V<br />

• Temp range: –40°C to +125°C (INA327)<br />

• Packaging: MSOP-8, MSOP-10<br />

Applications<br />

• Low-level transducer amplifier for<br />

bridges, load cells, thermocouples<br />

• Wide dynamic range sensor<br />

measurements<br />

• High-resolution test systems<br />

• Weigh scales<br />

• Multi-channel data acquisition systems<br />

• Medical instrumentation<br />

The INA326 uses a new, unique internal circuit topology that provides true rail-to-rail input. Unlike<br />

other instrumentation amplifiers, it can linearly process inputs to 20mV below the negative power<br />

supply rail, <strong>and</strong> 100mV above the positive power supply rail. Conventional instrumentation amplifier<br />

input topologies cannot deliver such wide dynamic performance.<br />

In most instrumentation amplifiers, the ability to reject common-mode signals is derived through a<br />

combination of input amplifier CMR <strong>and</strong> accurately matched resistor ratios. The INA326 converts the<br />

input voltage to a current, allowing the input amplifiers to accurately match <strong>and</strong> reject common-mode<br />

input voltage <strong>and</strong> power supply variation without the use of resistors.<br />

V IN–<br />

Current Monitor<br />

I R1<br />

Current Monitor<br />

I R1 R 1<br />

I R1 Current Monitor<br />

V IN+<br />

A1<br />

A2<br />

2I R1<br />

Current Monitor<br />

V+ V–<br />

0.1µF<br />

IR1<br />

2I R1<br />

V 0<br />

2I R1<br />

2I R1<br />

2I R1<br />

A3<br />

INA326<br />

INA326 functional block diagram.<br />

R 2 C 2<br />

IA COMMON<br />

2MHz B<strong>and</strong>width, Rail-to-Rail Output, Single-Supply Instrumentation <strong>Amplifier</strong>s<br />

INA332, INA2332<br />

Get samples, datasheets, <strong>and</strong> app reports at: www.ti.com/sc/device/INA332 <strong>and</strong> www.ti.com/sc/device/INA2332<br />

Key Features<br />

• High gain accuracy: G = 5, 0.07%, 2ppm/°C<br />

• High CMRR: 73dB DC, 50dB at 45kHz<br />

• Low bias current: 0.05pA<br />

• B<strong>and</strong>width: 2MHz<br />

• Slew rate: 5Vµs<br />

• Rail-to-rail output swing: (V+) –0.02V<br />

• Low quiescent current: 490µA max/ch<br />

• Packaging: MSOP-8 single, SSOP-14 dual<br />

Applications<br />

• Industrial sensors:<br />

• Bridge, RTD, thermocouple, position<br />

• Physiological amplifiers: ECG, EEG, EMG<br />

• Field utility meters<br />

• PCMCIA cards<br />

• Test equipment<br />

• Automotive instrumentation<br />

The INA332 <strong>and</strong> INA2332 are rail-to-rail output, low-power, gain = 5, CMOS instrumentation<br />

amplifiers that operate on 2.7V to 5.5V supplies. They offer excellent speed/power ratio with<br />

2MHz b<strong>and</strong>width <strong>and</strong> 490µA/channel supply current. Available shutdown/enable function adds<br />

additional power savings by reducing current to 0.01µA.<br />

V REF<br />

V IN –<br />

V IN +<br />

40kΩ<br />

G = 5 + (5R 2 /R 1 )<br />

10kΩ<br />

INA332 functional block diagram.<br />

R 1<br />

–<br />

10kΩ<br />

–<br />

A 1 –<br />

A 3<br />

+<br />

A 2<br />

+<br />

+<br />

V+<br />

V–<br />

40kΩ<br />

R G<br />

Shutdown<br />

R 2<br />

INA332<br />

V OUT<br />

<strong>Amplifier</strong> <strong>and</strong> <strong>Data</strong> <strong>Converter</strong> <strong>Selection</strong> <strong>Guide</strong> Texas Instruments 3Q 2006

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