器件名称: DI-129
功能描述: 33 W (60 W Peak) PVR Power Supply
文件大小: 668.71KB 共2页
简 介:Design Idea DI-129
PeakSwitch
Application PVR Device PKS606P
33 W (60 W Peak) PVR Power Supply
Power Output 33 W (60 W Pk) Input Voltage 195-265 VAC Output Voltage 3.3 V, 5 V, 17.5 V, 22 V Topology Flyback
Design Highlights
Small, low-cost EF25 core size delivers 60 W peak Low component count: only 47 parts High efciency: ≥76% at 33 W No-load power consumption <140 mW Meets EN55022 B conducted EMI limits
Operation
The yback converter shown in Figure 1 uses a member of the PeakSwitch family (U6, a PKS606P) to supply 33 W continuously and peak power pulses of up to 60 W. The controller in U6 receives feedback from the secondary through U5, and based on that feedback, enables or disables the switching of its integrated MOSFET to maintain regulation. A portion of both the 3.3 V and the 5 V outputs are fed into the TL431 (U2), which controls the current through the LED in U5. As the 3.3 V or the 5 V output voltages rise above
their set-point thresholds, U2 pulls additional current through the LED in U5. This in turn increases the base drive to Q1, increasing the current pulled out of the EN/UV pin of U6. Switching cycles are skipped once the EN/UV disable threshold current is exceeded. When the current out of the EN/UV pin falls below the disable threshold, switching cycles are re-enabled. A bias winding (T1, pins 4 and 5) on the transformer is rectied and ltered by D15 and C21, and supplies operating current to U6, through R14. The frequency jitter function within U6 an……
