器件名称: DI-26
功能描述: 7 W Digital Video Broadcast-Terrestrial (DVB-T) Supply
文件大小: 64.81KB 共2页
简 介:Design Idea DI-26 TOPSwitch-GX 7 W Digital Video
Broadcast-Terrestrial (DVB-T) Supply
Application DVB-T Device TOP242P Power Output 7W Input Voltage 195 to 265 VAC Output Voltage 2.5 V / 3.3 V / 6.2 V / 30 V Flyback
Topology
Design Highlights
Meets CISPR22B/EN55022B conducted EMI limits with output return grounded <0.5 W input power at zero load 132 kHz operation and programmable current limit allows small, low cost EF16 transformer for 7 W output Low component count design occupies 80 x 30 x 16 mm Integrated soft-start reduces start-up component stresses
Operation
The TOPSwitch-GX flyback supply provides 4 outputs, delivering 7 W from a 230 VAC ±15% input. The TOP242P was selected for low cost, the DIP-8 package removing the need for an external heat sink. Resistor R7 programs the internal TOP242P current limit to 78% of nominal, just above the level needed for full load at low line. This feature allows a more continuous transformer design for better efficiency and cross-regulation, without requiring a larger core size.
C15 2.2 nF Y1 D3 UF4002
T1
Resistor R12, C10 and L2 filter conducted EMI; R12 is a flame-proof fusible type, also functioning as a fuse. For lower cost, if the supply does not have to meet conducted EMI with the output connected to earth ground, the common mode choke can be replaced with a π filter. A Zener clamp (D11 and VR1) was selected over an RCD clamp to minimize zero load consumption. Secondary side feedback is taken from the 3.3 V ±5% outp……
