The AD623ARZ-RL from Analog Devices is a single-supply, rail-to-rail output instrumentation amplifier in an 8-pin SOIC package. It operates from 2.7 V to 12 V single supply (or \u00b12.5 V to \u00b16 V dual supply) with only 550 \u00b5A max supply current. Gain is set by a single external resistor from 1 (no resistor) to 1000. Key specs include 25 \u00b5V typical input offset voltage, 105 dB CMRR at G=100, 800 kHz bandwidth at G=1, 35 nV\/\u221aHz RTI noise at 1 kHz, and 0.1% gain error at G=1. The input common-mode range extends 150 mV below the negative rail. Output swings rail-to-rail. The A-grade specifies 200 \u00b5V max Vos and 2 \u00b5V\/\u00b0C max drift. -40\u00b0C to +85\u00b0C operating range. The -RL suffix denotes 2500-unit tape-and-reel packaging.<\/p>","protected":false},"excerpt":{"rendered":"
The AD623ARZ-RL from Analog Devices is a single-supply, rail-to-rail output instrumentation amplifier in an 8-pin SOIC package. It operates from 2.7 V to 12 V single supply (or \u00b12.5 V to \u00b16 V dual supply) with only 550 \u00b5A max supply current. Gain is set by a single external resistor from 1 (no resistor) to […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[19,13],"tags":[],"chip_brand":[165],"class_list":["post-2051","post","type-post","status-publish","format-standard","hentry","category-analog-linear-ics","category-integrated-circuits-ics","chip_brand-adi"],"acf":{"brief_explanation":"Single-supply in-amp, G=1-1000, 200\u00b5V Vos, 105dB CMRR, 800kHz BW, rail-to-rail out, SOIC-8, -40~85\u00b0C","date_code":"","package_case":"SOIC-8 (R) (4.9 x 3.9 x 1.45 mm, 1.27mm pitch)","in_stock":5913,"datasheet":"https:\/\/www.analog.com\/media\/en\/technical-documentation\/data-sheets\/ad623.pdf","price":"$3.52 (2.5K+ pcs)","product_introduction":"The AD623 is an integrated single-supply instrumentation amplifier from Analog Devices that delivers rail-to-rail output swing on a 3 V to 12 V supply. It follows the industry-standard 8-pin in-amp pinout (same as AD620, INA126), making it a drop-in upgrade in many existing designs. The AD623ARZ-RL is the A-grade version in SOIC-8 tape-and-reel packaging with 200-\u00b5V max input offset voltage.\n\nThe gain is set by a single external resistor according to G = 1 + (100 k\u03a9\/RG). With no external resistor, the device operates at unity gain (G = 1), simplifying PCB layout for applications that do not require amplification. The gain range of 1 to 1000 covers the vast majority of instrumentation applications, from bridge signal conditioning to thermocouple amplification.\n\nThe AD623's key advantage over competing in-amps is its ability to operate from a single 3-V supply while maintaining high CMRR. The CMRR remains stable up to 200 Hz, effectively rejecting power-line harmonics in industrial environments. At G = 10, CMRR is 90 dB minimum at 60 Hz with 1 k\u03a9 source imbalance \u2014 sufficient for most sensor applications.\n\nThe input common-mode voltage range extends 150 mV below the negative supply rail, enabling the AD623 to amplify signals at or slightly below ground in single-supply systems. This is critical for current-sense applications where the shunt voltage may be near ground.\n\nThe rail-to-rail output stage swings to within 10 mV of the supply rails under light load, maximizing dynamic range in low-voltage systems. The 550-\u00b5A max supply current is low enough for battery-powered medical instruments and portable data acquisition systems.\n\nThe B-grade (AD623BRZ) offers 100-\u00b5V max Vos and 1-\u00b5V\/\u00b0C max drift for higher-precision applications at additional cost.","working_principle":"**Three-Op-Amp Instrumentation Architecture:** The AD623 uses the classic three-op-amp instrumentation amplifier topology: two non-inverting input buffers (A1, A2) and a difference amplifier (A3). The input buffers present high impedance (2 G\u03a9) to the signal sources and provide gain. The difference amplifier rejects common-mode voltage and extracts the differential signal. The gain resistor RG connects between the RG pins and programs the gain of the input stage.\n\n**Gain Setting Mechanism:** Without RG (RG pins open), the input buffers operate as unity-gain followers, and the overall gain is 1. When RG is connected, the feedback loops of A1 and A2 include RG in their gain paths: G = 1 + (100 k\u03a9\/RG). The internal 100 k\u03a9 resistors are laser-trimmed to 0.01% accuracy, ensuring precise gain.\n\n**Common-Mode Rejection:** The difference amplifier A3 is laser-trimmed for resistor matching, achieving high CMRR. The CMRR increases with gain because the differential signal is amplified by the input stage before reaching A3, while the common-mode voltage is not. At G = 1000, CMRR exceeds 105 dB.\n\n**Rail-to-Rail Output Stage:** The output stage uses a complementary push-pull architecture that can swing to within millivolts of both supply rails. This is essential in 3-V and 5-V single-supply systems where output headroom is limited. The output can drive loads as low as 2 k\u03a9 to the rails.","pin_description":"
| Pin<\/th> | Name<\/th> | Type<\/th> | Description<\/th><\/tr><\/thead> | ||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1<\/td> | RG<\/td> | I<\/td> | Gain resistor connection; connect external RG between pins 1 and 8; leave open for G=1; G = 1 + (100k\/RG)<\/td><\/tr> | ||||||||||||||||||||||||||||
| 2<\/td> | VIN-<\/td> | I<\/td> | Inverting input; 2 G\u03a9 input impedance; 25 nA max bias current; common-mode range extends -150mV below negative rail<\/td><\/tr> | ||||||||||||||||||||||||||||
| 3<\/td> | VIN+<\/td> | I<\/td> | Non-inverting input; same characteristics as VIN-; differential input voltage up to supply voltage<\/td><\/tr> | ||||||||||||||||||||||||||||
| 4<\/td> | VS-<\/td> | P<\/td> | Negative supply; connect to GND for single-supply operation; -2.5V to -6V for dual supply; bypass with 0.1\u00b5F<\/td><\/tr> | ||||||||||||||||||||||||||||
| 5<\/td> | REF<\/td> | I<\/td> | Reference input; sets output baseline voltage; connect to GND for output referenced to ground; can be used for offset adjustment; 0.35mA max input current<\/td><\/tr> | ||||||||||||||||||||||||||||
| 6<\/td> | VOUT<\/td> | O<\/td> | Amplifier output; rail-to-rail swing; VOUT = (VIN+ - VIN-) \u00d7 G + VREF; can drive 2k\u03a9 loads<\/td><\/tr> | ||||||||||||||||||||||||||||
| 7<\/td> | VS+<\/td> | P<\/td> | Positive supply; +2.7V to +12V for single supply; +2.5V to +6V for dual supply; bypass with 0.1\u00b5F<\/td><\/tr> | ||||||||||||||||||||||||||||
| 8<\/td> | RG<\/td> | I<\/td> | Gain resistor connection; other end of RG; see pin 1<\/td><\/tr><\/tbody><\/table>","application_scenarios":"
|