# TL431CF

**HTC Korea TAEJIN Tech** · Voltage Reference · SOT-89-3

TL431CF from HTC Korea TAEJIN Tech, in a SOT-89-3. 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 | Reference | input | Reference voltage input of the shunt regulator, with VREF of 2.495 V typical (2.483 V to 2.507 V for TL431C at VKA = VREF, IK = 10 mA) and reference input current IREF of 1.8 µA typical (4.0 µA maximum). |
| 2 | Anode | power_in | Anode is the ground (common) terminal of the device, and the cathode current must be at least IK(MIN) = 0.5 mA for regulation. |
| 3 | Cathode | power_in | Cathode is the shunt regulator output terminal, rated for a cathode voltage VKA of 40 V recommended (42 V absolute maximum) and a continuous cathode current IK of 0.5 mA to 100 mA recommended (-100 mA to 150 mA absolute maximum). |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | HTC Korea TAEJIN Tech |
| 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 |
|---|---|---|---|---|---|---|---|
| Reference Input Voltage (TL431C, 0.5%) | VREF | 2.483 | 2.495 | 2.507 | V | VKA=VREF, IK=10mA | 4 |
| Deviation of Reference Input Voltage over full range | ΔVREF/ΔT |  | 8 | 20 | mV | VKA=VREF, IK=10mA, TA=Full Range | 4 |
| Ratio of Change in Reference Input Voltage to Change in Cathode Voltage (10V) | ΔVREF/ΔVKA |  | -1.4 | -2.7 | mV/V | ΔVKA=10V-VREF, IK=10mA | 4 |
| Ratio of Change in Reference Input Voltage to Change in Cathode Voltage (36V-10V) | ΔVREF/ΔVKA |  | -1 | -2 | mV/V | ΔVKA=36V-10V, IK=10mA | 4 |
| Reference Input Current | IREF |  | 1.8 | 4 | uA | IKA=10mA, R1=10kΩ, R2=∞ | 4 |
| Deviation of Reference Input Current over full range | ΔIREF/ΔT |  | 0.4 | 1.2 | uA | IK=10mA, R1=10kΩ, R2=∞, TA=Full Range | 4 |
| Minimum Cathode Current for Regulation | IK(MIN) |  |  | 0.5 | mA | VKA=VREF | 4 |
| Off-State Cathode Current | IK(OFF) |  | 0.17 | 0.9 | uA | VKA=36V, VREF=0 | 4 |
| Dynamic Impedance | ZKA |  | 0.27 | 0.5 | Ω | VKA=VREF, IK=1mA~100mA, f≤1kHz | 4 |
| Cathode Voltage | VKA |  |  | 40 | V | Minimum is VREF | 2 |
| Cathode Current | IK | 0.5 |  | 100 | mA |  | 2 |
| Cathode Voltage | VKA |  |  | 42 | V |  | 1 |
| Cathode Current Range (Continuous) | IK | -100 |  | 150 | mA | Continuous | 1 |
| Reference Input Current Range | IREF | -0.05 |  | 10 | mA |  | 1 |
| Junction Temperature Range | TJ | -40 |  | 150 | ℃ |  | 1 |
| Operating Temperature Range | TOPR | -40 |  | 125 | ℃ |  | 1 |
| Storage Temperature Range | TSTG | -65 |  | 150 | ℃ |  | 1 |
| Equivalent Full Range Temperature Coefficient |  |  | 50 |  | ppm/℃ | Stated in features list | 1 |

## CAD (KiCad official)

- Symbol: `TL431CF`
- Footprint: `Package_TO_SOT_SMD:SOT-89-3`
- 3D model: SOT-89-3 (KiCad packages3D, STEP)
- 3D model files: `tl431cf-etched.step` / `tl431cf-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `tl431cf.step` / `tl431cf.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [HTC Korea TAEJIN Tech datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8586183375883546624) (12 pp, sha256 `0a0d5fc0a3221190`, retrieved 2026-10-19, 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/tl431cf-datasheet.pdf)