Features and Benefits
- Pin Configurable as a Difference Amplifier, Inverting and Noninverting Amplifier
- Difference Amplifier
- Gain Range 1 to 13
- CMRR >75dB
- Noninverting Amplifier
- Gain Range 0.07 to 14
- Inverting Amplifier
- Gain Range -0.08 to -13
- Gain Error <0.04%
- Gain Drift < 3ppm/°C
- Wide Supply Range: Single 2.7V to Split ±18V
- Micropower: 100µA Supply Current
- Precision: 50µV Maximum Input Offset Voltage
- 560kHz Gain Bandwidth Product
- Rail-to-Rail Output
- Space Saving 10-Lead MSOP and DFN Packages
The LT1991 combines a precision operational amplifier with eight precision resistors to form a one-chip solution for accurately amplifying voltages. Gains from -13 to 14 with a gain accuracy of 0.04% can be achieved using no external components. The device is particularly well suited for use as a difference amplifier, where the excellent resistor matching results in a common mode rejection ratio of greater than 75dB.
The amplifier features a 50µV maximum input offset voltage and a gain bandwidth product of 560kHz. The device operates from any supply voltage from 2.7V to 36V and draws only 100µA supply current on a 5V supply. The output swings to within 40mV of either supply rail.
The resistors have excellent matching, 0.04% over temperature for the 450k resistors. The matching temperature coefficent is guaranteed less than 3ppm/°C. The resistors are extremely linear with voltage, resulting in a gain nonlinearity of less than 10ppm.
The LT1991 is fully specified at 5V and ±15V supplies and from -40°C to 85°C. The device is available in space saving 10-lead MSOP and low profile (0.8mm) 3mm × 3mm DFN packages.
- Handheld Instrumentation
- Medical Instrumentation
- Strain Gauge Amplifiers
- Differential to Single-Ended Conversion
Markets and Technologies
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (1)
DC819A Demo Board for:
LT1990 ±250V Input Range G = 1, 10, Micropower, Difference Amplifier
LT1995 30MHz, 1000V/µs Gain Selectable Amplifier
LT1991 Precision, 100µA Gain Selectable Amplifier
Documentation & Resources
R423 Reliability Data3/26/2018
DC819A - Demo Manual9/24/2009
3A Linear Regulator Can Be Easily Paralleled to Spread Power and Heat10/1/2011 LT Journal
Finally, High Voltage Current Sensing Made Easy5/1/2005 LT Journal
Versatile Op Amps Need No Resistors11/1/2004 LT Journal
Software & Systems Requirements
Tools & Simulations
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
Models for the following parts are available in LTspice:
Online Design Tool – BETA helps configure difference amplifier gain and topology with consideration for supply and output common mode limitations, analyzes noise and input impedance, and generates a downloadable LTSpice file for further simulation.
LT1991 Companion Parts
Recommended µModule Isolator
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Buy Now Pricing
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.