# OC5128

**OCX** · LED Drivers · ESOP-8

OC5128 from OCX, in a ESOP-8. 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 | GND | power_in | Ground reference for the chip. Connect to system ground with a short, wide trace to the current sense resistor return. |
| 2 | VDD | power_in | Chip supply pin. Fed from VIN through an external supply resistor RVDD; an internal shunt regulator clamps VDD at ~5.8V (max clamp current 10mA). UVLO rising threshold 4.1V with 0.4V hysteresis. |
| 3 | NC | unconnected | No connect. Leave floating. |
| 4 | SW | output | Switch node; drain of the internal 100V power MOSFET. Connects to the inductor / freewheeling diode in the buck topology. Absolute maximum voltage 100V. The exposed thermal pad is internally tied to SW. |
| 5 | CS | input | Inductor current sense input. Average CS voltage is regulated to 200mV (192-208mV) across the sense resistor RCS; LED current ILED = 0.2V / RCS. Route to RCS and GND with short, wide traces. |
| 6 | MODE | input | Brightness (dimming) select input with internal ~80kΩ pull-down. Float or tie to GND → full-brightness (100% ILED). Tie to a logic high (VDD) → half-brightness (ILED/2). Absolute max −0.3V to VDD+0.3V. |
| 7 | NC | unconnected | No connect. Leave floating. |
| 8 | NC | unconnected | No connect. Leave floating. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | OCX |
| Package | ESOP-8 |
| Category | LED-drv |
| Pins | 8 |

## CAD (KiCad official)

- Symbol: `OC5128`
- Footprint: `Package_SO:SOIC-8-1EP_3.9x4.9mm_P1.27mm_EP2.29x3mm`
- 3D model: ESOP-8 (KiCad packages3D, STEP)
- 3D model files: `oc5128-etched.step` / `oc5128-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `oc5128.step` / `oc5128.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [OCX datasheet](docs/oc5128-datasheet.pdf) (6 pp, sha256 `531c4e86661633eb`, retrieved 2026-08-17, 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:** `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/oc5128-datasheet.pdf)