LT1997-2: Precision, Wide Voltage Range, Gain Selectable Funnel Amplifier

30 May 2019

The LT1997-2 is an attenuating (funnel) difference amplifier that can be used to translate large differential signals to the low voltage range compatible with ADCs. It combines a precision operational amplifier with highly-matched resistors to form a one-chip solution to attenuate and level shift voltages accurately using no external components. It comes with three standard pin-selectable gain options (0.1, 0.2 and 0.25), which can be further combined to form gains from 0.0455 to 0.55 (attenuations of 1.82 to 22) with accuracy of 0.006% (60ppm). The LT1997-2 also works across a very wide input common-mode voltage range (±255V), enabling robust operation in demanding industrial environments. Its excellent resistor matching results in a common mode rejection ratio of greater than 105dB.

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The resistors maintain their excellent matching over temperature; the matching temperature coefficient is guaranteed less than 1ppm/°C. The resistors are extremely linear with voltage, resulting in a gain nonlinearity of less than 2ppm.

The LT1997-2 is fully specified at 5V and ±15V supplies and from −40°C to 125°C. The device is available in space saving 16-lead MSOP and 4mm × 4mm DFN14 packages.

Features and Benefits:

- Precision Attenuation: Gain = 0.1, 0.2, 0.25
- ±255V Common Mode Voltage Range
- 105dB Minimum CMRR (Gain = 0.1)
- 0.006% (60ppm) Maximum Gain Error
- 1ppm/°C Maximum Gain Error Drift
- 2ppm Maximum Gain Nonlinearity
- Wide Supply Voltage Range: 3.3V to 50V
- Rail-to-Rail Output
- 350µA Supply Current
- 80µV Maximum Op Amp Offset Voltage
- 1MHz –3dB Bandwidth (Gain = 1)
- Low-Power Shutdown: 20µA
- Space-Saving MSOP and DFN Packages

Applications:

- High Voltage to Low Voltage Level Translation
- ADC Driver
- Bidirectional Wide Common Mode Range Voltage and Current Sensing
- Industrial Data-Acquisition Front-Ends
- Replacement for Isolation Circuits
- Differential to Single-Ended Conversion

Product Lifecycle: Recommended for new designs. This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.

Evaluation Kit	Description
DC2551A	Demonstration Circuit 2551A is a Configurable Precision Amplifier featuring the LT1997