# TL431ASC

**PJSEMI** · Voltage Reference · SOT-23-3

TL431ASC from PJSEMI, in a SOT-23-3. 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 | Ref | input | Reference input that sets the programmable output voltage; Vref is approximately 2.495 V and the output is set with two external resistors. |
| 2 | Cathode | passive | Cathode is the regulated output; cathode voltage must be between VREF and 36 V and cathode current between 1 mA and 100 mA. |
| 3 | Anode | passive | Anode is the other terminal of the shunt path; the datasheet gives the cathode current range (continuous -100 to +150 mA absolute maximum) measured through the device. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | PJSEMI |
| Package | SOT-23-3 |
| 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 (TL431A 0.5%) | VREF | 2.483 | 2.495 | 2.507 | V | Fig1; VKA=VREF, IKA=10mA | 4 |
| Deviation of Reference Input Voltage Over Temperature | ΔVREF |  | 4.5 | 17 | mV | VKA=VREF, IKA=10mA, -40°C ≤ TA ≤ +85°C | 4 |
| Ratio of Change in Reference Input Voltage to Change in Cathode Voltage (10V to VREF) | ΔVREF/ΔVKA |  | -1 | -2.7 | mV/V | Fig2; IKA=10mA; ΔVKA=10V~VREF | 4 |
| Ratio of Change in Reference Input Voltage to Change in Cathode Voltage (36V to 10V) | ΔVREF/ΔVKA |  | -0.5 | -2 | mV/V | Fig2; IKA=10mA; ΔVKA=36V~10V | 4 |
| Reference Input Current | IREF |  | 1.5 | 4 | µA | Fig2; IKA=10mA, R1=10KΩ, R2=∞ | 4 |
| Deviation of Reference Input Current Over Full Temperature Range | ΔIREF |  | 0.4 | 1.2 | µA | Fig2; IKA=10mA, R1=10KΩ, R2=∞, -20°C ≤ TA ≤ +85°C | 4 |
| Minimum Cathode Current for Regulation | IKA(MIN) |  | 0.45 | 1 | mA | Fig1; VKA=VREF | 4 |
| Off-State Cathode Current | IKA(OFF) |  | 0.05 | 1 | µA | Fig3; VKA=36V, VREF=0 | 4 |
| Dynamic Impedance | ZKA |  | 0.15 | 0.5 | Ω | VKA=VREF, IKA=1~100mA, f≤1.0KHz | 4 |
| Cathode Voltage (absolute maximum) | VKA |  |  | 37 | V |  | 3 |
| Cathode Current Range (continuous) | IKA | -100 |  | 150 | mA |  | 3 |
| Operating Junction Temperature | TJ |  |  | 150 | °C |  | 3 |
| Storage Temperature Range | TSTG | -65 |  | 150 | °C |  | 3 |
| Cathode Voltage (recommended) | VKA |  |  | 36 | V | Minimum printed as VREF (not numeric); see review_required | 3 |
| Cathode Current (recommended) | IKA | 1 |  | 100 | mA |  | 3 |
| Operating Ambient Temperature Range | TOPR | -40 |  | 125 | °C |  | 3 |
| Junction-to-Ambient Thermal Resistance, SOT-23-3 | RθJA |  | 416 |  | °C/W | SOT-23-3 package | 3 |

## CAD (KiCad official)

- Symbol: `TL431ASC`
- Footprint: `Package_TO_SOT_SMD:SOT-23-3`
- 3D model: SOT-23-3 (KiCad packages3D, STEP)
- 3D model files: `tl431asc-etched.step` / `tl431asc-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `tl431asc.step` / `tl431asc.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [PJSEMI datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8604442943654805504) (10 pp, sha256 `7c0f5f7aa8485986`, 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/tl431asc-datasheet.pdf)