器件名称: DI-116
功能描述: 28 W Multiple Output Supply with <50 mW o-Load Consumption
文件大小: 448.77KB 共2页
简 介:Design Idea DI-116
TinySwitch-III
Application DVD / Set-top Box Device
28 W Multiple Output Supply with <50 mW No-Load Consumption
Power Output Input Voltage 90-265 VAC Output Voltage 5 V / 12 V / -12 V / -24 V Topology Flyback TNY280P 25 W (28 W pk)
Design Highlights
Simple, low cost, low parts count solution Low input power at no-load: <50 mW at 265 VAC Low standby power consumption: <90 mW input with 5 V, 5 mA load High efciency: >74% at 90 VAC >10 dBV EMI margin to EN55022B conducted EMI limits, even with output connected to safety earth ground Simple output overvoltage latching shutdown circuit protects load under fault conditions On-time extension provides 28 ms hold-up time
The internal MOSFET in U1 conducts current through the primary winding of T1 during each enabled switching cycle. When the primary current reaches the MOSFET current limit, it turns off and the energy in T1 is transferred to the secondary. The primary clamp (D5, VR3, R1, R2 and C3) limits the maximum peak drain voltage below the 700 V breakdown voltage of the internal MOSFET. Output overvoltage protection (OVP) is provided by U2, R12, R13, VR1 and VR2. If the feedback loop were to open circuit due to a failure of U3, VR1 or VR2 would turn on U2 causing the current into the BP/M pins of U1 to exceed 6.5 mA, and U1 to latch off. The values of VR1 and VR2 determine the output voltage at which this occurs. Once triggered, cycling the AC power resets the OVP latch. To reduce no-load input po……