OB3330XCPA from OB On Bright Elec, in a SOP-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	ZCD	input	Zero-current detection input, connected to the auxiliary winding via a resistor divider. Triggers a new PWM cycle when the voltage falls below the 0.3 V demagnetization threshold. Also monitors output OV (>4 V) and LED-short (<0.9 V for 10 ms) conditions. Absolute max -1 V to 7 V.
2	OCP_TH	bidirectional	OCP threshold-level setting pin. Sources ~28 uA (17-39 uA); an external resistor to GND programs the cycle-by-cycle peak-current limit: 0 Ω = 2.1 V, 33 kΩ = 1.8 V, 110 kΩ = 1.5 V. Absolute max -0.7 V to 7 V.
3	MULT	input	Analog multiplier input; senses the rectified AC half-wave via a resistor divider to shape the CS threshold for PFC. Working range 0-3 V, multiplier DC gain K ~0.91 1/V. Absolute max -0.7 V to 7 V.
4	COMP	bidirectional	Error-amplifier output / loop compensation pin. Clamped between 1.2 V and 6 V; EA gm ~80 uS, DC gain 60-70 dB, source/sink 32/100 uA. Connect an RC network to GND. Absolute max -0.7 V to 7 V.
5	CS	input	Primary-side current-sense input from the MOSFET-source resistor Rcs. Integrated 300 ns leading-edge blanking; propagation delay ~100 ns from OCP comparator to gate. LED current: ILED = (N/2)·(400 mV/Rcs). Absolute max -0.7 V to 7 V.
6	GND	power_in	Device ground reference for all internal circuitry and the CS return path.
7	GATE	output	Totem-pole gate-drive output for the external power MOSFET. Voh ≥8 V, Vol ≤1.5 V @ 100 mA; internally clamped to ~11-12.5 V to protect the MOSFET gate. Tr ~80 ns, Tf ~30 ns into 1 nF. Absolute max -0.7 V to 40 V.
8	VCC	power_in	IC supply, typically fed from an auxiliary winding via a startup resistor. UVLO(OFF/on) 15.2 V rising, UVLO(ON/off) 9 V falling; OVP at 30 V. Startup current ~5 uA (max 15 uA), operating current ~1.5-2.5 mA. Absolute max -0.3 V to 40 V.

Key specifications

Parameter	Value
Manufacturer	OB On Bright Elec
Package	SOP-8
Category	LED-drv
Pins	8

Ordering variants

Same part, different packaging or reel option.

OB3330XCPA

CAD (KiCad official)

Symbol: OB3330XCPA
Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
3D model: SOP-8 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`ob3330xcpa.step`	122 KB	You want the bare part, or you mark your own boards.
`ob3330xcpa-etched.step`	2.5 MB	You want the part with `OB3330XCPA` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 588 faces against 147 in the bare model. It survives export, section views, and rendering in any CAD tool, and it drops straight into KiCad or Fusion with no extra setup.

Provenance

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

Datasheet: OB On Bright Elec datasheet (10 pp, sha256 d2bab31d1ea8b9a2, 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