Zero-drift, 36-V in-amp has no 1/f corner for ease of use, highest accuracy

October 26, 2015 // By Graham Prophet
Texas Instruments says it has the first zero-drift, 36-V instrumentation amplifier, in the form of its INA188, that delivers high, “pinpoint” accuracy for precise DC and low-frequency measurements in applications such as test and measurement, medical, and industrial process control equipment.

The amp also eliminates the 1/f corner and features best-in-class offset drift to enable accurate measurement over the full extended industrial temperature range.

Th low offset drift optimises long-term temperature stability: the zero-drift architecture used in the INA188 delivers high accuracy for high-voltage precision-measurement applications. Compared to alternative solutions, it enables an offset voltage of 25 µV and a 33% lower offset-voltage drift of 80 nV/C to provide long-term temperature stability over the lifetime of the end equipment.

No 1/f corner and low DC noise enable precise measurements at low frequencies: the INA188 generates only 250 nVPP of noise from 0.1 Hz to 10 Hz, with no 1/f corner frequency between broadband and near-DC. When combined with the INA188's broadband noise floor of 12.5 nV/√Hz, the amplifier provides precision for low-frequency applications.

High voltage ensures signal integrity: capable of operating at up to 36V, the INA188 helps maintain signal integrity over the full extended temperature range by allowing larger gains than lower voltage instrumentation amplifiers.

Support tools include:

- Evaluation module (EVM): the universal instrumentation amplifier EVM (SO8) , is available for $25.

- Verify board-level signal integrity requirements and device behaviour with a free TINA-TI SPICE macromodel.

- TI Designs reference design: a three-terminal PLC reference design featuring the INA188 converts ±10-V or ±20-mA inputs to a single-ended output voltage for 5-V analogue-to-digital converters (ADCs). Additionally, the design features the REF3225 precision voltage reference integrated circuit.

- The TI Precision Amplifier Forum can locate solutions, get help, share knowledge, and solve problems with fellow engineers and TI experts.

- Vcm vs. Vout calculator: a standalone downloadable tool for instrumentation amplifiers plots the Vcm versus Vout curve given the designer's specific design requirements, including single- or dual-supply, gain and reference voltage.

In a 4.9 x 3.91-mm small outline integrated circuit (SOIC) package the part costs $1.85 (1,000). It will be available in early 4Q15 in a 4-mm-by-4-mm very