AD8369ARUZ

Amplifiers - Instrumentation, OP Amps, Buffer Amps

AD8369ARUZ application field and working principle

The AD8369ARUZ is an instrumentation amplifier (INA), buffer amplifier, and a precision voltage-to-current converter that operates at single-ended and differential supply voltages over the specified common-mode input range of 0 V to VS+. The device consists of an integrated signal path that includes a precision low-noise amplifier, an R-2R resistor ladder network to set the gain, and a signal buffer to provide a high output-voltage capability. It employs an R-2R topology to create a wide dynamic range of gains from 0.25 to 16 V/V. This device provides single-ended input and output capability with a wide common-mode range along with a low-noise input stage.

The AD8369ARUZ offers several design advantages, including excellent channel-to-channel CMRR and low input-voltage noise. It operates from a single 2.375 V to 5.5 V or differential 4.75 V to 11 V supply voltages and is specified across the –40°C to +85°Ctemperature range.

Due to its gain-setting resistor ladder network, the AD8369ARUZ can be configured for a variety of gains, providing flexibility in board-level design. Connecting a resistor between the GAIN/RST pin and AGND establishes the gain.

The AD8369ARUZ is ideal for use in a wide range of applications including medical, automotive, industrial and consumer systems. Possible applications include precision instrumention and amplifiers, proportional-to-voltage and current-commanded systems, smart sensors, and data acquisition.

Working Principle

The AD8369ARUZ is a gain-setting INA that combines a high-impedance low-noise high-gain block, a resistor ladder network, and a configurable buffer amplifier. The device features wide common-mode range, low-noise, low-distortion, and low residual offset voltage. The AD8369ARUZ is characterized at a single-ended supply voltage from 2.375 V to 5.5 V and a differential 4.75 V to 11 V supplies.

The device consists of an input buffer, an R-2R resistor ladder network, which is used to set the gain, and an output buffer. The input buffer converts the differential input signals to a differential signal that is proportional to the difference between the input signals. The R-2R resistor ladder network sets the gain. Finally, the output buffer converts the signal back to a single-ended signal that is suitable for further processing.

The gain of the AD8369ARUZ is set by connecting a resistor between the GAIN/RST pin and AGND. The resistor value determines the gain, which is from 0.25 V/V to 16 V/V. The gain is set to its minimum value of 0.25 V/V when the GAIN/RST pin is tied to AGND. The maximum gain achieved is 16 V/V when a 100 kΩ resistor is connected to the GAIN/RST pin. Once the gain is set, the device can be used in any application requiring a precise low-noise gain-setting INA. Since the gain is set using an external resistor, the device provides flexibility in board-level designs.

The AD8369ARUZ features a wide common-mode range of 0 V to VS+. It is specified with a low input noise of 3 µV RMS with a 1 kHz bandwidth and has a high common-mode rejection ratio (CMRR) of 94 dB min. It also has a low residual offset voltage of 2 mV with a gain of 1 V/V or greater. The device requires a single or differential supply voltage and is specified over the temperature range from –40°C to +85°C.

The AD8369ARUZ features excellent stability and exceptional common-mode and input-voltage noise performance, making it an excellent choice for precision instrumentation, medical, and automotive applications. The device can also be used to control a wide range of signals including proportional-to-voltage and current-commanded systems, smart sensors, and data acquisition systems.