AD623 Instrumentation Amplifier: Pinout, Circuit and Alternatives

AD623 is an integrated, single- or dual-supply instrumentation amplifier, which delivers rail-to-rail output swing using supply voltages from 3 V to 12 V. 

The AD623 offers greater user flexibility by allowing single gain set resistor programming and by conforming to the 8-lead industry standard pinout configuration.

With no external resistor, the AD623 is configured for unity single gain (G = 1), after an external resistor, the AD623 can be programmed for gains of up to 1000 times.

AD623 maintains the smallest error by increasing excellent AC common-mode rejection ratio (ACCMRR) with increasing gain. Line noise and harmonics are rejected due to CMRR up to 200HZ. 

It has a wide common-mode input range and can amplify signals with a common-mode voltage as low a s 150mv below ground. It can still maintains superior  performance with dual  and single polarity power supplies (2.5 to 6V). 

Low power consumption, wide power supply voltage range, and full power supply amplitude output make AD623 an ideal choice for battery power supply. 

When working under low power supply voltage, the full power supply amplitude output stage maximizes the dynamic range. It can replace the discrete instrumentation amplifier design, and provides good linearity in the smallest space, and the temperature stability is very reliable.

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● Easy to use

● Gain range: 1 to 1000

● Rail-to-rail output swing

● Gain accuracy: 0.10% (G=1)

● 800 kHz bandwidth (G = 1)

● Gain accuracy: 0.35% (G》1)

● High-precision DC performance

● Excellent dynamic specifications

● Noise: RTI noise: 35nV/√Hz (at 1kHz)

● 20 µs settling time to 0.01% (G = 10)

● The gain is set by one  external resistor

● Available in 8-Pin PDIP,SOIC and VSSOP packages

● Low power consumption, 550μA maximum power supply current

● The input voltage range extends 150mV below the ground voltage (single power supply)

Analog Devices Inc. AD623ANZ technical specifications, attributes, parameters and parts with similar specifications to Analog Devices Inc. AD623ANZ.

The AD623 is an Instrumentation Amplifier with rail-to-rail feature. It also operates at a very low current of 550nA making it suitable for battery operated applications.

Instrumentation amplifier: Instrumentation amplifier is a type of differential amplifier that has buffer amplifiers connected to their input pins. This eliminates the need for impedance matching, thus making it practically suitable for measurement and test equipments.

Rail-to-rail Op-Amp: The output pin of a normal op-amp will not be able to provide voltage that is equal to the supply voltage. This is because of the output stage transistors which prevent the amplifier from reaching the maximum positive voltage or minimum negative voltage. Rail-to-rail op-Amp overcomes this problem and hence the output pin can reach either positive rail voltage or negative rail voltage.

The AD623 only requires a resistor to sets its gain value and hence can be easily set up. A very basic commonly used circuit for AD623 is shown below.

The IC is powered using the pin 7 and pin 4, here I have used a singly supply of +5V hence the pin 4 is grounded. If a dual supply voltage is used the pin 4 will be provided with negative voltage. The non - inverting pin (pin 2) and the inverting pin (pin 3) is connected the signal which has to be amplified or compared base on the application of the Op-Amp. The Reference pin (pin 5) is normally grounded along with pin 4, the reference pin is used to direct the output towards a voltage when the difference voltage between the inverting and the non-inverting pin is 0V.

The gain of an op-amp can be set by simply connecting the right value of resistor across the pin +Rg (pin 8) and the pin –Rg (pin 1). Here I have connected a resistor of value 500Ω which will set the op-amp at a gain value of 100. The formulae to calculate the value of gain from R is given below

Alternatively you can also use the chart below which has the value of resistor and standard gain values listed.

ADI (NASDAQ: ADI) is the world leader in the design, manufacture and marketing of a broad portfolio of high-performance analog, mixed-signal, and digital signal processing (DSP) integrated circuits (IC) electronic devices. Since our establishment in 1965, we have been focusing on solving engineering challenges related to signal processing in electronic equipment. Our signal processing products are used by more than 100,000 customers around the world, and play an important role in converting, regulating and processing real-world phenomena such as temperature, pressure, sound, light, speed and motion into electrical signals for use in a wide array of Electronic equipment.

Download datasheets and manufacturer documentation for Analog Devices Inc. AD623ANZ.