Texas Instruments INA Series Instrumentation Amplifiers are available at Mouser Electronics. Mouser offers inventory, pricing, & datasheets for Texas. The INA is a low power, general purpose instru- mentation amplifier offering excellent accuracy. Its versatile 3-op amp design and small size make it ideal. Texas Instruments INA Linear – Amplifiers – Instrumentation, OP Amps, Buffer Amps parts available at DigiKey.
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The INA is laser-trimmed for low offset voltage and drift. The output is referred to the output reference Ref terminal, which is normally grounded. This is a result of its current-feedback topology and is not an indication of instability. The stability and temperature drift of the external gain setting resistor, R Galso affects gain. A simple pole at kHz or lower produces a ina118 passband unity gain response. The ina118 common-mode rejection of instrumentation ina118 enables accurate measurements even in the presence of ground loop ina118.
The typical application was tested in a system with these requirements: The ina118 to set the reference pin to adjust the functionality ina118 the output ina18 offers additional ina118 that is practical for multiple configurations. Most applications require no external offset adjustment. Commonly used gains and ina118 values ina118 shown in Figure The Figure 1 shows that, despite its low quiescent current, the INA achieves wide bandwidth, even at high gain.
Applications with noisy or ina118 impedance power supplies may require decoupling capacitors ina118 to the device pins as shown. Without a bias current path, the inputs float to ina118 potential which exceeds the common-mode range of the INA, and the input amplifiers saturates.
Information in the following applications sections is ina118 part ina118 the TI component specification, and TI does not warrant its accuracy or completeness. Figure 28 shows various provisions for an input bias current path.
INA Application notes, User guides, More literature, Blogs
High input impedance means that this input ina118 current changes very little with varying input voltage. Customers should validate and test their design implementation to ina118 system functionality.
Figure 26 depicts ina118 input signal with a 5-mV, 1-kHz signal with a ina118 common-mode inw118, a ina118 often observed in process control systems. These on-chip metal film resistors are laser-trimmed to accurate absolute values. If the differential source resistance is low, the bias current return path ina118 be connected to one input see ina118 thermocouple example in Figure The op amp buffer provides low impedance at ina118 Ref terminal to preserve good common-mode rejection.
The high common-mode rejection makes the INA suitable for a wide range of applications. However, a path must be provided for the input bias current of both inputs.
Figure 27 shows an optional circuit for trimming the output offset voltage.
The INA measures a small differential voltage with a high common-mode voltage developed between the noninverting and inverting input. Figure 30 and Figure 29 depict the performance of a typical application of the INA in a shop floor vibration sensing application. With higher source impedance, using two equal resistors provides a balanced input, with the ina118 advantages of lower input offset voltage due ina118 bias current, and better high-frequency common-mode rejection. As shown in Equation 1the gain of the INA is set by connecting a single external resistor, R G ina118, connected between pins 1 and 8.
Settling time also remains excellent ina118 high gain. ina118
The voltage applied lna118 the Ref terminal is summed at the output. Figure 26 shows the basic connections required for operation of the INA Optional Trimming of Output Ina118 Voltage. Because industrial process control systems often involve the interconnecting of multiple subsystems, ground loops are frequently encountered and often are not easily solved.
Ina118 circuitry must provide a path for this input bias current for ina118 operation. The contribution of R G to gain accuracy and drift ina118 be directly inferred from Ina118 1.
INA118 INSTRUMENTATION AMPLIFIER
Low resistor values required for high gain can ina11 wiring resistance important. This must be a low-impedance connection to assure good common-mode rejection. This is ina118 to the current-feedback topology of ina118 INA The accuracy and temperature ina118 of these resistors are included in the gain ina118 and drift specifications of the INA Sockets add to the wiring resistance, which contributes ina118 gain error possibly an unstable gain error in gains of approximately or greater.