Description

The OPA387, OPA2387, and OPA4387 (OPAx387) family of precision amplifiers offers state-of-the-art performance. With zero-drift technology, the OPAx387 offset voltage and offset drift provide unparalleled long-term stability. With a mere 570 µA of quiescent current, the OPAx387 are able to achieve 5.7 MHz of bandwidth, a broadband noise of 8.5 nV/√Hz, and a 1/f noise at 177 nVPP. These specifications are crucial to achieve extremely-high precision and no degradation of linearity in 16-bit to 24-bit analog to digital converters (ADCs). The OPAx387 feature flat bias current over temperature; therefore, little to no calibration is needed in high input impedance applications over temperature.
All versions are specified over the industrial temperature range of –40°C to +125°C.

 

Caractéristiques

• Ultra-low offset voltage: ±2 µV (maximum, tested)
• Zero drift: ±0.003 µV/°C
• Low-input bias current: 150 pA (maximum, tested)
• Low noise: 8.5 nV√ Hz at 1 kHz
• No 1/f noise: 177 nVPP (0.1 Hz to 10 Hz)
• Common-mode input range ±100 mV beyond supply rails
• Gain bandwidth: 5.7 MHz
• Quiescent current: 570 μA per amplifier
• Single supply: 1.7 V to 5.5 V
• Dual supply: ±0.85 V to ±2.75 V
• EMI and RFI filtered inputs

 

Applications

• Electronic thermometer
• Weigh scale
• Temperature transmitter
• Ventilators
• Data acquisition (DAQ)
• Semiconductor test
• Lab and field instrumentation
• Merchant network and server PSU
• Analog input module
• Pressure transmitter

 

Vue d'ensemble

The OPAx387 family of zero-drift amplifiers is engineered with state-of-the-art, proprietary, precision zero-drift technology. These amplifiers offer ultra-low input offset voltage and drift, and achieve excellent input and output dynamic linearity. The OPAx387 operate from 1.7 V to 5.5 V, are unity-gain stable, and are designed for a wide range of general-purpose and precision applications. The OPAx387 strengths also include a 5.7-MHz bandwidth, 8.5-nV/√Hz noise spectral density, and no 1/f noise, making the OPAx387 an excellent choice for interfacing with sensor modules, and buffering high-fidelity, digital-to-analog converters (DACs).

 

Input Bias Current

During normal operation, the typical input bias current of the OPAx387 is 30 pA. The device exhibits low drift over the full temperature range of –40°C to +125°C. There are no antiparallel diodes between the input pins (+IN and –IN); therefore, the differential input maximum voltage is limited only by diodes connected to the supply voltage pins. However, use caution in cases where the input differential voltage exceeds the nominal operating input differential voltage. When inputs are separated, the switching offset-cancellation path internal to the amplifier exceeds normal operating conditions, and can potentially create long settling behavior upon return to normal operation.

 

EMI Susceptibility and Input Filtering

Operational amplifiers can exhibit sensitivity to electromagnetic interference (EMI). Typically, conducted EMI (that is, EMI that enters the device through conduction) is more commonly observed than radiated EMI (that is, EMI that enters the device through radiation). When conducted EMI enters the operational amplifier, the dc offset at the amplifier output can shift from the nominal value. This shift is a result of signal rectification associated with the internal semiconductor junctions. Although all operational amplifier pin functions can be affected by EMI, the input pins are likely to be the most susceptible. The OPAx387 operational amplifier family incorporates an internal input low-pass filter that reduces the amplifier response to EMI. Both common-mode and differential-mode filtering are provided by the input filter.

 

Informations sur l'application

The OPAx387 are unity-gain stable, precision, operational amplifiers featuring state-of-the-art, zero-drift technology. The use of proprietary zero-drift circuitry gives the benefit of low input offset voltage over time and temperature, as well as lower 1/f noise component. As a result of the high PSRR, the devices work well in applications that run directly from battery power without regulation. The OPAx387 family is optimized for full rail-to-rail input, allowing for low-voltage, single-supply operation or split-supply use. These miniature, high-precision, low-noise amplifiers offer high-impedance inputs that have a common-mode range 100 mV beyond the supplies without input crossover distortion, and a rail-to-rail output that swings within 5 mV of the supplies under normal test conditions. The OPAx387 precision amplifiers are designed for upstream analog signal-chain applications in low or high gains, as well as downstream signal-chain functions, such as DAC buffering.