器件名称: DI-74
功能描述: 1.25 W Non-Isolated Constant Current LED Driver
文件大小: 279.98KB 共2页
简 介:Design Idea DI-74 LinkSwitch-TN 1.25 W Non-Isolated
Constant Current LED Driver
Application LED Driver Device LNK304P Power Output 1.25 W Input Voltage 85-265 VAC Output Voltage 12.5 V, 100 mA Topology Buck-Boost
Design Highlights
Universal AC input range – single design worldwide Accurate and stable constant current output Small size and weight Low cost, low component count solution replaces passive capacitor or resistor droppers Fail safe topology – protects load High efciency (>60% at 85 VAC) Scalable output power using larger LinkSwitch-TN devices Meets EN55022 B EMI limits
LinkSwitch-TN uses ON/OFF control to regulate the output current. When the current into the FEEDBACK (FB) pin exceeds 49 A, MOSFET switching is disabled for the next switching cycle. The 49 A threshold is specied at a pin voltage of 1.65 V (±7%), allowing it to be used as a reference. The voltage developed across R3, which is averaged by C4, represents the output current. When this voltage exceeds 2 V, the voltage on the FB pin, via divider of R1 and R2, exceeds 1.65 V and >49 A current is fed into the pin. The 2 V across R3 sets an output current of 100 mA, or 25 mA for each string of LEDs. If the load is disconnected or the output is shorted, no feedback is provided and LinkSwitch-TN enters auto-restart (5% on time). To prevent a high output voltage under no load the optional voltage feedback circuit can be included by adding VR1 and D4. The voltage of VR1 is selected to be above the norma……
