# T49SM12MLDDE2X

**Yajingxin** · Crystals · HC-49S-SMD

T49SM12MLDDE2X from Yajingxin, in a HC-49S-SMD. 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 | 1 | passive | Terminal 1 of a two-terminal crystal; either orientation. |
| 2 | 2 | passive | Terminal 2 of a two-terminal crystal; either orientation. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Yajingxin |
| Package | HC-49S-SMD |
| Category | Crystals, Oscillators, Resonators |
| Pins | 2 |

## Electrical characteristics

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

| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| Frequency Tolerance at 25℃ (調整頻差) |  | -20 |  | 20 | ppm | at 25℃ | 2 |
| Stability over operation temperature (溫度頻差) |  | -30 |  | 30 | ppm |  | 2 |
| Equivalent Resistance (諧振電阻) |  |  |  | 40 | Ω |  | 2 |
| Shunt Capacitance (Co) (靜態電容) | Co | 0 |  | 7 | pF |  | 2 |
| Insulation Resistance (絕緣電阻) |  | 500 |  |  | MΩ | at DC 100V | 2 |
| Aging (老化率) |  |  |  | 3 | ppm/year |  | 2 |
| Operating Temperature Range (工作溫度範圍) |  | -30 |  | 85 | ℃ |  | 2 |
| Storage Temperature Range (儲存溫度範圍) |  | -40 |  | 85 | ℃ |  | 2 |
| Nominal Frequency (標稱頻率) |  |  | 12 |  | MHz |  | 2 |
| Load Capacitance (CL) (負載電容) | CL |  | 20 |  | pF |  | 2 |
| Drive Level (激勵功率) |  |  | 100 |  | uw |  | 2 |

## CAD (KiCad official)

- Symbol: `T49SM12MLDDE2X`
- Footprint: `Crystal:Crystal_SMD_HC49-SD`
- 3D model: HC-49S-SMD (KiCad packages3D, STEP)
- 3D model files: `t49sm12mldde2x-etched.step` / `t49sm12mldde2x-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `t49sm12mldde2x.step` / `t49sm12mldde2x.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Yajingxin datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8603104522004668416) (5 pp, sha256 ``, retrieved 2026-10-14, tier: lcsc)
- **Datasheet language:** Chinese. Pin names, descriptions, and specs on this page were extracted and translated to English by ds2sf; the linked PDF is the manufacturer original.
- **Extractor:** parts-factory `2.0.0` / `extract_pins`, primary `crystal numbering` (convention), consensus `off` (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/t49sm12mldde2x-datasheet.pdf)