# TL431APA

**PJSEMI** · Voltage Reference · SOP-8

TL431APA from PJSEMI, in a SOP-8. 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 | Cathode | passive | Cathode is the regulated output terminal; the TL431 sinks cathode current from 1 mA to 100 mA and operates with VKA from VREF up to 36 V (absolute maximum 37 V). |
| 2 | Anode | passive | Anode is the common return terminal of the shunt regulator, and cathode current flows from the cathode into the anode. |
| 3 | Anode | passive | Anode is the common return terminal of the shunt regulator, and cathode current flows from the cathode into the anode. |
| 4 | NC | unconnected | No internal connection; this pin is not connected inside the device. |
| 5 | NC | unconnected | No internal connection; this pin is not connected inside the device. |
| 6 | Anode | passive | Anode is the common return terminal of the shunt regulator, and cathode current flows from the cathode into the anode. |
| 7 | Anode | passive | Anode is the common return terminal of the shunt regulator, and cathode current flows from the cathode into the anode. |
| 8 | Ref | input | Reference input to the internal approximately 2.495 V reference; the output voltage is set by the external divider from this pin, with typical reference input current of 1.5 µA. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | PJSEMI |
| Package | SOP-8 |
| Category | Power Management (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 |
|---|---|---|---|---|---|---|---|
| Reference Input Voltage (TL431A, 0.5%) | VREF | 2.483 | 2.495 | 2.507 | V | VKA=VREF, IKA=10mA (Fig1) | 4 |
| Deviation of Reference Input Voltage Over Temperature | ΔVREF |  | 4.5 | 17 | mV | VKA=VREF, IKA=10mA, -40°C≤TA≤+85°C (Fig1) | 4 |
| Ratio of Change in Reference Input Voltage to Change in Cathode Voltage (10V to VREF) | ΔVREF/ΔVKA |  | -1 | -2.7 | mV/V | IKA=10mA, ΔVKA=10V~VREF (Fig2) | 4 |
| Ratio of Change in Reference Input Voltage to Change in Cathode Voltage (36V to 10V) | ΔVREF/ΔVKA |  | -0.5 | -2 | mV/V | IKA=10mA, ΔVKA=36V~10V (Fig2) | 4 |
| Reference Input Current | IREF |  | 1.5 | 4 | µA | IKA=10mA, R1=10KΩ, R2=∞ (Fig2) | 4 |
| Deviation of Reference Input Current Over Full Temperature Range | ΔIREF |  | 0.4 | 1.2 | µA | IKA=10mA, R1=10KΩ, R2=∞, -20°C≤TA≤+85°C (Fig2) | 4 |
| Minimum Cathode Current for Regulation | IKA(MIN) |  | 0.45 | 1 | mA | VKA=VREF (Fig1) | 4 |
| Off-State Cathode Current | IKA(OFF) |  | 0.05 | 1 | µA | VKA=36V, VREF=0 (Fig3) | 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 | Continuous | 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 (symbol, not a number) | 3 |
| Cathode Current | IKA | 1 |  | 100 | mA |  | 3 |
| Operating Ambient Temperature Range | TOPR | -40 |  | 125 | °C |  | 3 |
| Junction-to-Ambient Thermal Resistance (SOP-8) | RθJA |  | 208 |  | °C/W | SOP-8 package | 3 |

## CAD (KiCad official)

- Symbol: `TL431APA`
- Footprint: `Package_SO:SOIC-8_3.9x4.9mm_P1.27mm`
- 3D model: SOP-8 (KiCad packages3D, STEP)
- 3D model files: `tl431apa-etched.step` / `tl431apa-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `tl431apa.step` / `tl431apa.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/8603392355316232192) (10 pp, sha256 `7c0f5f7aa8485986`, retrieved 2026-10-18, 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/tl431apa-datasheet.pdf)