# TX4221

**XDS** · DC-DC Converters · SOP-8

TX4221 from XDS, in a SOP-8. Pinout and pin descriptions extracted from the manufacturer datasheet by ds2sf; symbol, footprint, and 3D from KiCad-official CAD.

## Pinout

| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | DRV | output | Gate drive output for the external power MOSFET. Rise/fall time ~50 ns into 500 pF; absolute maximum 8 V. |
| 2 | VDD | power_in | Chip supply input. Operating range 5-40 V (absolute max 45 V). UVLO threshold ~4.8 V; operating current ~2.5 mA at 200 kHz. |
| 3 | EN | input | Chip enable, active high. VIH >= 3.2 V, VIL <= 0.8 V. Absolute max 45 V. Pulling EN low puts the chip in standby (~75 uA). |
| 4 | ROSC | input | External resistor to GND sets the switching frequency: Fs = 4.83e7 / (ROSC + 1.08e5) Hz. With ROSC tied directly to GND the internal frequency defaults to ~450 kHz; typical values 100-330 kOhm (150 kHz at 330 kOhm). |
| 5 | FB | input | Output voltage feedback pin. Internal reference V_FB = 1.000 V (975-1025 mV). Vout = (R1+R2)/R1 * V_FB. Absolute max 6.5 V. |
| 6 | NC | unconnected | No connection; leave floating (悬空). |
| 7 | GND | power_in | Device ground reference. |
| 8 | VCS | input | MOSFET switch current-limit sense input. Over-current threshold typ. 250 mV (240-260 mV). Peak inductor current IPK <= 0.25 / R_CS. Absolute max 6.5 V. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | XDS |
| Package | SOP-8 |
| Category | PMIC |
| Pins | 8 |

## Electrical characteristics

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

| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| 工作电压 | VDD | 5 |  | 40 | V |  | 4 |
| 过流保护阀值 | TH_VCS | 240 | 250 | 260 | mV |  | 4 |
| FB脚采样电压 | V_FB | 975 | 1000 | 1025 | mV |  | 4 |
| 输入电压 | VDD | -0.3 |  | 45 | V |  | 3 |
| 使能 | EN | -0.3 |  | 45 | V |  | 3 |
| 驱动端 | DRV | -0.3 |  | 8 | V |  | 3 |
| 最大输入 | V_MAX | -0.3 |  | 6.5 | V | TOFF/FB/CS | 3 |
| 工作结温度 | TA | -40 |  | 85 | ℃ |  | 3 |
| 存储温度 | T_STG | -40 |  | 120 | ℃ |  | 3 |
| 焊接温度 | T_SD |  |  | 240 | ℃ | 焊接，10秒左右 | 3 |
| 静电耐压值 | V_ESD | 2 |  |  | KV | 人体模型 | 3 |
| 功耗 | P_SOP8 |  |  | 0.8 | W | P_SOP8 | 3 |
| 欠压保护电压 | V_UVLO |  | 4.8 |  | V |  | 4 |
| 工作电流 | IOP |  | 2.5 |  | mA | FoP=200KHz | 4 |
| 待机输入电流 | I_INQ |  | 75 |  | uA | 无负载， EN 为低电平 | 4 |
| 工作频率 | F_TOFF |  | 150 |  | KHz | ROSC=330K | 4 |
| EN端_高电平 | H_EN |  | 3.2 |  | V |  | 4 |
| EN端_低电平 | L_EN |  | 0.8 |  | V |  | 4 |
| DRV驱动上升时间 | T_RISE |  | 50 |  | ns | DRV脚接500P电容 | 4 |
| DRV驱动下降时间 | T_FALL |  | 50 |  | ns | DRV脚接500P电容 | 4 |
| 过温保护 | TH_OTP |  | 140 |  | ℃ |  | 4 |
| 最大占空比 | D_MAX |  | 87 |  | % | VFB=0V | 4 |

## CAD (KiCad official)

- Symbol: `TX4221`
- Footprint: `Package_SO:SOIC-8_3.9x4.9mm_P1.27mm`
- 3D model: SOP-8 (KiCad packages3D, STEP)
- 3D model files: `tx4221-etched.step` / `tx4221-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `tx4221.step` / `tx4221.glb` are the bare package body.

## 3D model downloads

Two STEP files. Same geometry, different body top:

| File | Size | Use it when |
|---|---|---|
| [`tx4221.step`](tx4221.step) | 122 KB | You want the bare part, or you mark your own boards. |
| [`tx4221-etched.step`](tx4221-etched.step) | 1.2 MB | You want the part with `TX4221` already on it. |

The marking in the etched file is real recessed geometry cut into the solid, not a
texture or a decal: 324 faces against 147 in the bare model. It
survives export, section views, and rendering in any CAD tool, and it drops straight
into KiCad or Fusion with no extra setup.

## Provenance

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

- **Datasheet:** [XDS datasheet](docs/tx4221-datasheet.pdf) (6 pp, sha256 `baf00f6a9445dd43`, retrieved 2026-08-17, 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:** `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).

[Datasheet PDF](docs/tx4221-datasheet.pdf)