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On Semi NCP1308 50W四输出STB电源解决方案

文章出处:8gled.com作者:格烁光电发表时间:2018-07-23
佛山代孕-孕期频道2z34【和您一起看世界】On Semi 公司的NCP1308控制器把电流模式调制器和退磁检测器集成在一起,可以在任何的负载/线路条件下保证有更宽的导通模式,过流保护自动恢复,内部软起动时间1.0s,在AC/DC转换器和离线电池充电器等有广泛用途.本文介绍了NCP1308主要特性, 内部电路架构图, 典型应用电路图以及50W四输出机顶盒(STB)电源电路图和材料清单(BOM).

50 W Four--Output Internal Power Supply for Set Top Box

The NCP1308 combines a true current mode modulator and a demagnetization detector to ensure full borderline/Critical Conduction Mode in any load/line conditions and minimum drain voltage switching (Quasi-Resonant operation). Due to its inherent skip cycle capability, the controller enters burst mode as soon as the power demand falls bELow a predetermined level. As this happens at low peak current, no audible noise can be heard. An internal 10us timer prevents the free-run frequency to exceed a high frequency (therefore below the 150 kHz CISPR-22 EMI starting limit), while the skip adjustment capability lets the user select the frequency at which the burst foldback takes place.

The Dynamic Self-Supply (DSS) drastically simplifies the transformer design in avoiding the use of an auxiliary winding to supply the NCP1308. This feature is particularly useful in applications where the output voltage varies during operation (e.g. battery chargers). Thanks to its high-voltage technology, the IC is directly connected to the high-voltage DC rail. As a result, the short-circuit trip point is not dependent upon any VCC auxiliary level.

The transformer core reset detection is done through an auxiliary winding which, brought via a dedicated pin. If an OVP is detected on the VCC pin, the IC permanently latches off.Finally, the continuous feedback signal monitoring implemented with an Overcurrent fault Protection circuitry (OCP) makes the final design rugged and reliable.

NCP1308主要特性:

Free-Running Borderline/Critical Mode Quasi-Resonant Operation

Current-Mode with Adjustable Skip Cycle Capability

Dynamic Self-Supply Type of VCC

Auto-Recovery Overcurrent Protection

Improved UVLO for VCC below 10 V

Latching Overvoltage Protection on VCC

500 mA Peak Current Source/Sink Capability

Internal 1.0 ms Soft-Start

Internal 10us Minimum TOFF

Adjustable Skip Level

Internal Temperature Shutdown

Internal Leading Edge Blanking

Direct Optocoupler Connection

SPICE Models Available for TRANsient Analysis

This is a Pb-Free Device

NCP1308典型应用:

AC-DC Adapters for Notebooks, etc.

Offline Battery Chargers

Consumer Electronics (DVD Players, Set-Top Boxes, TVs, etc.)

Auxiliary Power Supplies (USB, Appliances, TVs, etc.)

图1.NCP1308内部电路架构图

图2.NCP1308典型应用电路图

50W四输出机顶盒(STB)电源

This reference document describes a built--and--tested, GreenPoint® solution for a 40 W (40 W nominal power, 50 W peak power) set--top box (STB) power supply. This document 代孕产子-【让爱让家完整UjkP】助孕频道presents the results of various secondary rectification and regulation techniques thatwere used to find the highest practical efficiency scheme for a four--output, 40 watt set top box power supply.

The power supply design is built around ON Semiconductor’s NCP1308 Current--Mode controller, on the primary side, using free running quasi—resonance operation. The secondary side offers four outputs (+5 V, --5 V, 3.3 V and 12 V). The +5 V output is the main channel with the closed PWMloop while the 3.3 Voutput is derived by using the NCP1587 in a buck (step--down) DC—DC topology with synchronous rectification. The 12Voutput is derived from+5 V by stacking the 12 V secondary winding onto the 5 V winding.

图3.参考设计电路简化框图

图4.50W四输出机顶盒(STB)电源外形图

图5.机顶盒(STB)电源电路图

50W四输出机顶盒(STB)电源材料清单(BOM):


佛山代孕-孕期频道2z34【和您一起看世界】 On Semi NCP1308 50W四输出STB电源解决方案原创编辑请注明出来http://m.hzjjn.com

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