器件名称: DI-91
功能描述: 12 W Universal Input CV Adapter
文件大小: 426.93KB 共2页
简 介:Design Idea DI-91 TinySwitch-III
Application General Purpose Device TNY278P
12 W Universal Input CV Adapter
Power Output 12 W Input Voltage 85-265 VAC Output Voltage 12 V Topology Flyback
Design Highlights
No-load consumption <50 mW at 265 VAC (R8 tted) Active mode efciency >75% (CEC standard: ≥71%) BP/M pin capacitor value selects MOSFET current limit (ILIMIT–1, ILIMIT, or ILIMIT+1): for design exibility Output OVP function senses overvoltage on the output through the primary bias winding Accurate (±5%), auto-recovering, hysteretic thermal shutdown function maintains safe PCB temperatures Auto-restart function protects against output short circuits and open feedback loops > 3.2 mm package pin creepage: reliable operation in high humidity and high pollution environments
The use of an E-shield in the transformer, a low-noise drainnode clamp (R2, C4 and D5), a single Y capacitor (C5) and the devices switching frequency jitter function enable a low-cost pi (π) lter (C1, L1 and C2) to attenuate conducted EMI enough to provide more than 10 dB of margin to EN550022 requirements (see Figure 4). The clamp circuit Zener (VR1) only conducts briey during startup and at worst-case overload, just before the auto-restart function is activated. Although TinySwitch-III family members do not need a bias winding to operate, one was used in this design to take advantage of the ICs output OVP detection function. If an open loop fault causes an overvoltage on the output, VR2 will condu……