# ADS1251U

**Texas Instruments** · Analog To Digital Converters (ADC) · SOIC-8

ADS1251U 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 | +VIN | input | Positive input of the differential analog input; accepts analog input voltage from GND - 0.3V to VDD + 0.3V with maximum input current of ±10mA continuous. |
| 2 | -VIN | input | Negative input of the differential analog input; accepts analog input voltage from GND - 0.3V to VDD + 0.3V with maximum input current of ±10mA continuous. |
| 3 | +VDD | power_in | Power-supply voltage input; nominal +5V, operating range 4.75V to 5.25V, quiescent current 1.5 to 2mA. |
| 4 | CLK | input | Device system clock, CMOS-compatible Schmitt-Trigger input; nominal 8MHz, used to determine modulator frequency and data output rate. |
| 5 | DOUT/DRDY | output | Serial data output and data ready indicator; pulses LOW when new data loaded into output register, shifts data MSB-first on falling edge of SCLK. |
| 6 | SCLK | input | Serial clock input, CMOS-compatible Schmitt-Trigger input; operates independently from CLK up to 8MHz; holding HIGH initiates modulator reset for synchronization or enters power-down mode. |
| 7 | GND | power_in | Ground reference for analog and digital sections; should connect to analog ground plane with trace connection to digital ground plane. |
| 8 | VREF | power_in | Reference voltage input; accepts 0.5V to VDD with typical load current of 32µA at 8MHz clock; buffered reference recommended. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Texas Instruments |
| Package | SOIC-8 |
| Category | Data Acquisition |
| Pins | 8 |

## CAD (KiCad official)

- Symbol: `ADS1251U`
- Footprint: `Package_SO:SOIC-8_3.9x4.9mm_P1.27mm`
- 3D model: SOIC-8 (KiCad packages3D, STEP)
- 3D model files: `ads1251u-etched.step` / `ads1251u-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `ads1251u.step` / `ads1251u.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/ads1251) (25 pp, sha256 `114414aea45f64d9`, retrieved 2026-09-26, tier: lcsc)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.2`, primary `claude-haiku-4-5-20251001` (text), consensus `claude-sonnet-4-6` (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/ads1251u-datasheet.pdf)