# BL8503-40PRM

**BL Shanghai Belling** · Voltage Regulators - Linear, Low Drop Out (LDO) Regulators · SOT-23-3L

BL8503-40PRM from BL Shanghai Belling, in a SOT-23-3L. 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 | Vss | power_in | Ground reference (0V). Common return for input and output. Connect to system ground with a low-impedance path. |
| 2 | Vout | power_out | Regulated output voltage (4.0V nominal, ±2%) for the -40 option. Delivers up to 250mA. Requires a 1µF output capacitor (tantalum recommended) for loop stability. |
| 3 | Vin | power_in | Supply voltage input, 1.5V to 10V absolute max (recommended max 8V). Requires a 1µF input capacitor (tantalum recommended). For Vout=4.0V, Vin must exceed Vout + dropout (~4.4V @ 250mA). |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | BL Shanghai Belling |
| Package | SOT-23-3L |
| Category | PMIC |
| Pins | 3 |

## Ordering variants

- `BL8503-40PRM`
- `BL8503-40PRMPSM`
- `BL8503-40PRMPSA`
- `BL8503-40PRMPSB`
- `BL8503-40PRMPT`

## CAD (KiCad official)

- Symbol: `BL8503-40PRM`
- Footprint: `Package_TO_SOT_SMD:SOT-23-3`
- 3D model: SOT-23-3L (KiCad packages3D, STEP)
- 3D model files: `bl8503-40prm-etched.step` / `bl8503-40prm-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `bl8503-40prm.step` / `bl8503-40prm.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [BL Shanghai Belling datasheet](docs/bl8503-40prm-datasheet.pdf) (None pp, sha256 `8f6684221c2cf4c4`, retrieved 2026-08-17, tier: lcsc)
- **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/bl8503-40prm-datasheet.pdf)