Precision, 100µA Gain Selectable Amplifier

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.

Applications

* Handheld Instrumentation

* Medical Instrumentation

* Strain Gauge Amplifiers

* Differential to Single-Ended Conversion

* 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