# TL431BQPK

**Texas Instruments** · Voltage Reference · SOT-89-3

TL431BQPK from Texas Instruments, in a SOT-89-3. 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 | REF | input | Reference input pin; establishes the threshold voltage for the internal 2.5V reference and receives feedback for voltage programming. |
| 2 | ANODE | power_in | Anode or common pin; typically connected to ground or return path; internally attached to substrate. |
| 3 | CATHODE | bidirectional | Cathode output pin; serves as the shunt regulator output terminal and sinks cathode current from 1 mA to 100 mA. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Texas Instruments |
| Package | SOT-89-3 |
| Category | Power Management (PMIC) |
| Pins | 3 |

## Electrical characteristics

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

| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| 基准电压 (Reference voltage), TL431BQ | Vref | 2483 | 2495 | 2507 | mV | VKA = Vref，IKA = 10mA | 15 |
| 整个温度范围内的基准输入电压偏差 (Reference input voltage deviation over temperature range) | VI(dev) |  | 14 | 34 | mV | VKA = Vref，IKA = 10mA | 15 |
| 基准电压变化与阴极电压变化之比 (Change in Vref to change in VKA ratio) | ΔVref / ΔVKA |  | -1.4 | -2.7 | mV/V | IKA = 10mA，ΔVKA = 10V - Vref | 15 |
| 基准电压变化与阴极电压变化之比 (Change in Vref to change in VKA ratio) | ΔVref / ΔVKA |  | -1 | -2 | mV/V | IKA = 10mA，ΔVKA = 36V - 10V | 15 |
| 基准输入电流 (Reference input current) | Iref |  | 2 | 4 | µA | IKA = 10mA，R1 = 10kΩ，R2 = ∞ | 15 |
| 整个温度范围内的基准输入电流偏差 (Reference input current deviation over temperature range) | II(dev) |  | 0.8 | 2.5 | µA | IKA = 10mA，R1 = 10kΩ，R2 = ∞ | 15 |
| 调节的最小阴极电流 (Minimum cathode current for regulation) | Imin |  | 0.4 | 0.7 | mA | VKA = Vref | 15 |
| 关闭状态阴极电流 (Off-state cathode current) | Ioff |  | 0.1 | 0.5 | µA | VKA = 36V，Vref = 0 | 15 |
| 动态阻抗 (Dynamic impedance) | /ZKA/ |  | 0.2 | 0.5 | Ω | VKA = Vref，f ≤ 1kHz，IKA = 1mA 至 100mA | 15 |
| 阴极电压 (Cathode voltage) | VKA |  |  | 36 | V | Minimum printed as Vref (symbol, no numeric value given) | 6 |
| 连续阴极电流范围 (Continuous cathode current range) | IKA | 1 |  | 100 | mA |  | 6 |
| 自然通风条件下的工作温度范围 (Operating free-air temperature range) | TA | -40 |  | 125 | °C | TL43xxQ | 6 |
| 阴极电压 (Cathode voltage) | VKA |  |  | 37 | V |  | 6 |
| 连续阴极电流范围 (Continuous cathode current range) | IKA | -100 |  | 150 | mA |  | 6 |
| 基准输入电流 (Reference input current) | II(ref) | -0.05 |  | 10 | mA |  | 6 |
| 工作结温范围 (Operating virtual junction temperature range) | TJ |  |  | 150 | °C |  | 6 |
| 贮存温度范围 (Storage temperature range) | Tstg | -65 |  | 150 | °C |  | 6 |
| 结至环境热阻 (Junction-to-ambient thermal resistance) | RθJA |  | 52 |  | °C/W | PK package column | 6 |
| 结至外壳（顶部）热阻 (Junction-to-case (top) thermal resistance) | RθJC(top) |  | 9 |  | °C/W | PK package column | 6 |

## CAD (KiCad official)

- Symbol: `TL431BQPK`
- Footprint: `Package_TO_SOT_SMD:SOT-89-3`
- 3D model: SOT-89-3 (KiCad packages3D, STEP)
- 3D model files: `tl431bqpk-etched.step` / `tl431bqpk-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `tl431bqpk.step` / `tl431bqpk.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/tl431) (86 pp, sha256 `313277b9351e61ed`, retrieved 2026-09-22, 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 0.2`, primary `claude-haiku-4-5-20251001` (text), consensus `claude-sonnet-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/tl431bqpk-datasheet.pdf)