# INA121UA

**Texas Instruments** · Instrumentation Amplifiers · SOIC-8

INA121UA from Texas Instruments, in a SOIC-8. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

## Pinout

| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | RG | passive | Gain-setting resistor terminal; external RG connects between pins 1 and 8 to set G = 1 + 50kΩ/RG (1 to 10,000 V/V). |
| 2 | V-IN | power_in | Inverting input of the instrumentation amplifier, with internal over-voltage protection to ±40V. |
| 3 | V+IN | power_in | Non-inverting input of the instrumentation amplifier, with internal over-voltage protection to ±40V. |
| 4 | V- | power_in | Negative supply; supply range is ±2.25V to ±18V. |
| 5 | Ref | input | Output reference terminal, normally grounded and must be a low-impedance connection to preserve CMR (8Ω in series degrades CMR to about 80dB at G = 1). |
| 6 | VO | output | Amplifier output, referred to the Ref pin, with short-circuit current of ±14mA. |
| 7 | V+ | power_in | Positive supply; supply range is ±2.25V to ±18V. |
| 8 | RG | passive | Gain-setting resistor terminal; external RG connects between pins 1 and 8 to set G = 1 + 50kΩ/RG. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Texas Instruments |
| Package | SOIC-8 |
| Category | Amplifiers/Comparators |
| Pins | 8 |

## CAD (KiCad official)

- Symbol: `INA121UA`
- Footprint: `Package_SO:SOIC-8_3.9x4.9mm_P1.27mm`
- 3D model: SOIC-8 (KiCad packages3D, STEP)
- 3D model files: `ina121ua-etched.step` / `ina121ua-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `ina121ua.step` / `ina121ua.glb` are the bare package body.

## Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

- **Datasheet:** [Texas Instruments datasheet](https://www.ti.com/cn/lit/gpn/ina121) (22 pp, sha256 `df8d2ff139ef60c7`, retrieved 2026-10-07, tier: lcsc)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-haiku-5-5` (text), consensus `claude-sonnet-5-5` (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
- **CAD:** KiCad official libraries (CC-BY-SA 4.0).

[Datasheet PDF](docs/ina121ua-datasheet.pdf)