INA128
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TI precision instrumentation amplifier, SOIC-8. Gain 1-10000 set by one resistor, high CMRR, low drift. Datasheet-verified.
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markdownINA128
Texas Instruments · Instrumentation amplifier · SOIC-8
A precision instrumentation amplifier in SOIC-8, for pulling a small differential signal out of a noisy environment. One external resistor across the two RG pins sets the gain anywhere from 1 to 10000 (G = 1 + 50k/RG), and the three-op-amp topology gives very high common-mode rejection so shared noise on both inputs cancels. Low offset voltage and drift make it the front end for bridge sensors (load cells, pressure), thermocouples, current-shunt sensing, and biopotential measurement. A REF pin sets the output's ground reference. Runs on split supplies from plus/minus 2.25 to plus/minus 18 V.
Pinout
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | RG | passive | Gain-setting pin. For gains greater than 1, place a gain resistor between pin 1 and pin 8. Gain is set as G = 1 + 50kΩ/RG. Leave open for G = 1. |
| 2 | VIN- | input | Inverting (negative) analog input of the instrumentation amplifier. Input common-mode voltage range is (V-)+2V to (V+)-2V; safe input voltage is ±40V with RS = 0Ω. |
| 3 | VIN+ | input | Non-inverting (positive) analog input of the instrumentation amplifier. Input common-mode voltage range is (V-)+2V to (V+)-2V; safe input voltage is ±40V with RS = 0Ω. |
| 4 | V- | power_in | Negative supply rail. Dual-supply range ±2.25V to ±18V; single-supply operation V+ = 4.5V to 36V with V- = 0V. Decouple locally to ground. |
| 5 | REF | input | Reference input that sets the output DC reference level. Must be driven by a low-impedance source or connected directly to ground; any source impedance here directly degrades CMRR. |
| 6 | VO | output | Amplifier output. VO = G × (VIN+ - VIN-) + VREF, where G = 1 + 50kΩ/RG. Short-circuit protected to VS/2 continuously. |
| 7 | V+ | power_in | Positive supply rail. Dual-supply range ±2.25V to ±18V; single-supply 4.5V to 36V with V- = 0V. Decouple locally with a 0.1µF ceramic capacitor. |
| 8 | RG | passive | Gain-setting pin. For gains greater than 1, place a gain resistor between pin 1 and pin 8. Gain is set as G = 1 + 50kΩ/RG. Leave open for G = 1. |
Key specifications
| Parameter | Value |
|---|---|
| Type | Instrumentation amplifier |
| Gain | 1 to 10000 (G = 1 + 50k/RG) |
| Gain set | single external resistor (RG) |
| CMRR | 120 dB at G=100 |
| Offset voltage | 50 µV max |
| Supply | ±2.25 to ±18 V |
| Quiescent current | ~700 µA |
| Package | SOIC-8 |
Ordering variants
Same part, different packaging or reel option.
INA128UA (SOIC-8)INA128U (SOIC-8, tape & reel)
CAD (KiCad official)
- Symbol:
Amplifier_Instrumentation:INA128 - Footprint:
Package_SO:SOIC-8_3.9x4.9mm_P1.27mm - 3D model: SOIC-8 (KiCad packages3D)
- 3D model files:
ina128-etched.step/ina128-etched.glbcarry the MPN laser-etched on the die in a toggleableAdom.LaserEtchgroup (Fusion-ready);ina128.step/ina128.glbare the bare package body.
Provenance
Data extracted from the manufacturer datasheet, not a distributor listing:
- Datasheet: Texas Instruments datasheet (42 pp, sha256
1b13f3f996838202, retrieved 2026-08-17, tier: manufacturer) - Extractor:
ds2sf(Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate. - CAD: KiCad official libraries (CC-BY-SA 4.0).