Low Power, Single Resistor Gain Programmable, Precision Instrumentation Amplifier

The LT1168 is a micropower, precision instrumentation amplifier that requires only one external resistor to set gains of 1 to 10,000. The low voltage noise of 10nV/√Hz (at 1kHz) is not compromised by low power dissipation (350µA typical for ±15V supplies). The wide supply range of ±2.3V to ±18V allows the LT1168 to fit into a wide variety of industrial as well as battery-powered applications.

The high accuracy of the LT1168 is due to a 20ppm maximum nonlinearity and 0.4% max gain error (G = 10). Previous monolithic instrumentation amps cannot handle a 2k load resistor whereas the nonlinearity of the LT1168 is specified for loads as low as 2k. The LT1168 is laser trimmed for very low input offset voltage (40µV max), drift (0.3µV/°C), high CMRR (90dB, G = 1) and PSRR (103dB, G = 1). Low input bias currents of 250pA max are achieved with the use of superbeta processing. The output can handle capacitive loads up to 1000pF in any gain configuration while the inputs are ESD protected up to 13kV (human body). The LT1168 with two external 5k resistors passes the IEC 1000-4-2 level 4 specification.

The LT1168 is a pin-for-pin improved second source for the AD620 and INA118. The LT1168, offered in 8-pin PDIP and SO packages, requires significantly less PC board area than discrete op amp resistor designs. These advantages make the LT1168 the most cost effective solution for precision instrumentation amplifier applications.

Applications

* Bridge Amplifiers

* Strain Gauge Amplifiers

* Thermocouple Amplifiers

* Differential to Single-Ended Converters

* Differential Voltage to Current Converters

* Data Acquisition

* Battery-Powered and Portable Equipment

* Medical Instrumentation

* Scales

* Supply Current: 530µA Max

* Meets IEC 1000-4-2 Level 4 (±15kV) ESD Tests with Two External 5k Resistors

* Single Gain Set Resistor: G = 1 to 10,000

* Gain Error: G = 10, 0.4% Max

* Input Offset Voltage Drift: 0.3µV/°C Max

* Gain Nonlinearity: G = 10, 20ppm Max

* Input Offset Voltage: 40µV Max

* Input Bias Current: 250pA Max

* PSRR at AV =1: 103dB Min

* CMRR at AV = 1: 90dB Min

* Wide Supply Range: ±2.3V to ±18V

* 1kHz Voltage Noise: 10nV/√Hz

* 0.1Hz to 10Hz Noise: 0.28µVP-P

* Available in 8-Pin PDIP and SO Packages