# RS121XF

**Jiangsu RUNIC Tech** · Operational Amplifier · SOT-23-5

RS121XF from Jiangsu RUNIC Tech, in a SOT-23-5. 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 | OUT | output | Amplifier output, rail-to-rail, with the short-circuit output current specified at 25 mA. |
| 2 | V- | power_in | Negative supply rail; the part operates from 2.5 V to 5.5 V across V+ to V-, and the absolute maximum V+ to V- is 7.0 V. |
| 3 | +IN | input | Non-inverting input; common-mode range is -0.1 V to 5.6 V with Vs = 5.5 V, and inputs are diode-clamped to the rails, so signals more than 0.5 V beyond the rails must be limited to 10 mA. |
| 4 | -IN | input | Inverting input with the same limits as +IN: common-mode range -0.1 V to 5.6 V at Vs = 5.5 V, and input current limited to 10 mA when swinging more than 0.5 V beyond the rails. |
| 5 | V+ | power_in | Positive supply rail; the part operates from 2.5 V to 5.5 V, and the absolute maximum V+ to V- is 7.0 V. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Jiangsu RUNIC Tech |
| Package | SOT-23-5 |
| Category | Amplifiers/Comparators |
| Pins | 5 |

## Electrical characteristics

Limits as printed in the datasheet (page.json `metadata.characteristics` carries them as data).

| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| Operating Voltage Range | Vs | 2.5 |  | 5.5 | V | 25°C | 3 |
| Input Offset Voltage | Vos |  | 0.8 | 5 | mV | 25°C | 3 |
| Input Bias Current | IB |  | 1 | 10 | pA | 25°C | 3 |
| Input Offset Current | Ios |  | 1 | 10 | pA | 25°C | 3 |
| Common-Mode Voltage Range | Vcm | -0.1 |  | 5.6 | V | Vs=5.5V, 25°C | 3 |
| Output Swing From Rail |  |  | 3 |  | mV | RL = 2KΩ, 25°C | 3 |
| Output Short-Circuit Current | Iout |  | 25 |  | mA | 25°C | 3 |
| Slew Rate | SR |  | 0.05 |  | V/us | 25°C | 3 |
| Gain-Bandwidth Product | GBP |  | 0.15 |  | MHz | 25°C | 3 |
| Input-Referred Voltage Noise | en |  | 77 |  | nV/√Hz | f = 1 kHz, 25°C | 3 |
| Input-Referred Voltage Noise | en |  | 39 |  | nV/√Hz | f = 10 kHz, 25°C | 3 |
| Quiescent Current/Amplifier | IQ |  | 12 |  | uA | 25°C | 3 |
| Supply Current in Shutdown | IQ(OFF) |  |  | 1 | uA | 25°C | 3 |
| Turn-off time | tOFF |  | 3 |  | us | 25°C | 3 |
| Turn-on time | tON |  | 20 |  | us | 25°C | 3 |
| Shut Down logic-low threshold | VL |  |  | 0.8 | V | Shut Down, 25°C; referenced to (V-) | 3 |
| Amplifier Is Active logic-high threshold | VH | 2 |  |  | V | Amplifier Is Active, 25°C; referenced to (V-) | 3 |
| Input Terminals Voltage |  | -0.5 |  | 0.5 | V | Input terminals; upper limit printed as (V+)+0.5V | 2 |
| Input Terminals Current |  | -10 |  | 10 | mA |  | 2 |
| Storage Temperature |  | -65 |  | 150 | °C |  | 2 |
| Operating Temperature |  | -40 |  | 125 | °C |  | 2 |
| Junction Temperature |  |  |  | 150 | °C |  | 2 |
| Package Thermal Resistance (junction-to-ambient) |  |  | 200 |  | °C/W | SOT23-5, SOT23-6; TA = +25°C | 2 |
| Operating Temperature Range |  | -40 |  | 125 | °C | Temperature range per ordering information | 2 |

## CAD (KiCad official)

- Symbol: `RS121XF`
- Footprint: `Package_TO_SOT_SMD:SOT-23-5`
- 3D model: SOT-23-5 (KiCad packages3D, STEP)
- 3D model files: `rs121xf-etched.step` / `rs121xf-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `rs121xf.step` / `rs121xf.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Jiangsu RUNIC Tech datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8588902218330755072) (14 pp, sha256 `9418922fc6c089ef`, retrieved 2026-10-09, 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/rs121xf-datasheet.pdf)