# WS3412 Product Description

## Features
️· Internal 550V Power MOSFET
️· Active PFC for High Power Factor and Low THD
️· Critical Conduction Mode Operation
️· System Efficiency up to 95%
️· No auxiliary winding required
️· Excellent Line and Load Regulation
️· ±3% LED Output Current Accuracy
️· Thermal Regulation Function
️· LED Short/Open Protection
️· Current Sensing Resistor Open Protection
️· Auto Fault Recovery
️· Available in SOP8 Package

## Applications
️· E27 LED Bulb, Spot Light
️· PAR30, PAR38 Lamp
️· T8/T10 LED String
️· Other LED Lighting

## Typical Application
️· Non-isolated Buck APFC Offline LED Driver

## Description
️· High precision non-isolated buck driver with active PFC
️· Designed for universal input offline constant current LED lighting
️· Integrates 550V power MOSFET
️· Precise LED output current control with few external components
️· Rich protection functions: LED open/short circuit, CS resistor open circuit, cycle-by-cycle current limit (all auto-recovery)
️· Thermal regulation function reduces output current when over temperature
️· Ultra low startup and operating current

## Pin Configuration (SOP8 Package)

Name	Pin No.	Description
COMP	1	Loop Compensation Node
GND	2	Ground
VCC	3	Power Supply Pin
FB	4	Feedback Voltage Input Pin
D	5/6	Internal HV Power MOSFET Drain
CS	7/8	Current Sense Pin

## Electrical Characteristics (VCC=8V, TA=25℃)
*Refer to datasheet for detailed specifications regarding voltage, current, resistance, and temperature ratings.*

## Application Information
️· Start Up: VCC pin capacitor charged by startup resistor. System switches at 10kHz initially, achieving soft start.
️· Constant Current Control: Utilizes floating ground structure for high precision output control. LED current calculated via: I = 200mV / Rcs (where Rcs is the current sensing resistor).
️· Feedback Network: Senses output current zero crossing, with FB falling threshold at 0.2V.
️· Protection Functions: Includes LED open/short circuit protection, CS resistor protection, and thermal regulation.
️· Thermal Regulation: Output current reduces at 150°C to regulate temperature.

## PCB Layout Guidelines
️· Bypass capacitor on VCC should be close to the pins.
️· Power ground path for current sense resistor should be short, wide, and close to IC ground.
️· Signal ground for COMP and FB components should be connected to IC GND with short traces, separate from power ground.
️· Minimize the area of the main current loop.
️· Keep feedback resistor divider close to FB pin.
️· Maximize copper area on DRAIN pin for thermal dissipation.
️· Avoid PCB materials that easily absorb moisture.

## Package Information
️· SOP8 Package available. Refer to datasheet for dimensions.