OnSemi NPC1337 60W適配器參考設計方案

關鍵詞： OnSemi , NPC1337 , 適配器

OnSemi公司的NCP1337是一款結合電流模式調節器和退磁檢測器的芯片，以充分確保邊界線/臨界傳導模式在任何負載/傳輸線條件連同最低漏電壓開關（準-諧振操作）。因為Soxyless概念，變壓器鐵心重置檢測在內部完成，沒有使用任何外部信號。根據CISPR-22 EMI限制標準，內部頻率被限制于130kHz，防止控制器操作達到150kHz。該芯片具有過載保護重啟功能，一旦過載，設備會自動重啟恢復。本文主要介紹NCP1337芯片、芯片特性、應用方向及內部結構圖。本文還介紹了采用NCP1337芯片作為主芯片的60W參考設計方案，給出該方案的介紹、方案原理圖、PCB制板圖及元器件清單列表。

The NCP1337 combines a true current mode modulator and a demagnetization detector which ensures full Borderline/Critical Conduction Mode in any load/line conditions together with minimum drain voltage switching (Quasi−Resonant operation). The transformer core reset detection is done internally, without using any external signal, due to the Soxyless concept. The frequency is internally limited to 130 kHz, preventing the controller to operate above the 150 kHz CISPR−22 EMI starting limit.

By monitoring the feedback pin activity, the controller enters skip mode as soon as the power demand falls below a predetermined level. As each restart is softened by an internal Soft−Skip_, and as the frequency cannot go below 25 kHz, no audible noise can be heard.

The NCP1337 also features an efficient protective circuitry which, in presence of an overcurrent condition, disables the output pulses and enters a safe burst mode, trying to restart. Once the default has gone, the device auto−recovers. Also included is a bulk voltage monitoring function (known as brown−out protection), an adjustable overpower compensation, and a VCC OVP. The controller immediately restarts after any of these conditions, unless the fault timer has timed out. Finally, an internal 4.0 ms soft−start eliminates the traditional startup stress.

NCP1337主要特性：

• Free−Running Borderline/Critical Mode Quasi−Resonant Operation
• Current−Mode
• Soft−Skip Mode with Minimum Switching Frequency for Standby
• Auto−Recovery Short−Circuit Protection Independent of Auxiliary Voltage
• Overvoltage Protection
• Brown−Out Protection
• Two Externally Triggerable Fault Comparators (one for a disable function, and the other for a permanent latch)
• Internal 4.0 ms Soft−Start
• 500 mA Peak Current Drive Sink Capability
• 130 kHz Max Frequency
• Internal Leading Edge Blanking
• Internal Temperature Shutdown
• Direct Optocoupler Connection
• Dynamic Self−Supply with Levels of 12 V (On) and 10 V (Off)
• SPICE Models Available for TRANsient and AC Analysis
• These are Pb−Free Devices*

NCP1337應用：
• 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.)

2013-1-13 11:51:02 上傳

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圖1. NCP1337內部方框圖

NCP1337ADAPGEVB方案介紹：

This design using NCP1337 offers a perfect solution for portable DVD, LCD TV, or monitor and notebook adapter applications. This adapter provides effective protection functions such as over-load protection, over-voltage protection, shortcircuit protection and brown-out protection. Thanks to the quasi-resonant operation and synchronous rectifier, this adapter has high efficiency and improved EMI performance. The standby consumption is lower because of the cycle skipping and soft ripple mode.

NCP1337ADAPGEVB方案原理圖：