器件名称: DI-117
功能描述: 15 W, 12 V Adapter with <100 mW No-Load Consumption
文件大小: 262.83KB 共2页
简 介:Design Idea DI-117
TinySwitch-III
Application Adapters / General Purpose Device
15 W, 12 V Adapter with <100 mW No-Load Consumption
Power Output 15 W Input Voltage 90-265 VAC Output Voltage 12 V Topology Flyback
TNY279P
Design Highlights
Simple, low cost, low parts count solution Low input power at no-load: <100 mW at 265 VAC High efciency >81% at 90 VAC Meets CEC requirements for active mode efciency (79 % vs. 73.5 % requirement) >10 dBV margin to EN55022B conducted EMI limits Simple, primary-side output overvoltage latching shutdown protects load under fault conditions Low line frequency leakage current <10 A
Operation
The TNY279 (U1) in the 8-pin DIP package selected for the yback design in Figure 1 is ideal for adapter applications. The arrangement of the four SOURCE pins on one side of the package allows a small metal heatsink to be inserted. This allows the device to operate in a sealed adapter with an external ambient of 40 °C.
L4 1 mH C5 1 nF R5 R6 1 kV 240 k 240 k
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, the controller turns it off, and the energy in T1 is transferred to the output. Schottky diode D7 and capacitor C8 rectify and lter the output. Inductors L3 and capacitor C9 attenuate the switching ripple on the output. Capacitor C3 selects the standard current limit of U1. For higher efciency, the next larger (TNY280P) de……