On Semi 公司的NCP1219是有動態自偏壓電源的PWM" title="PWM">PWM控制器,具有極好的待機功耗,采用帶斜率補償的固定頻率電流模式運作,頻率在65kHz和100kHz選擇,不需要輔助繞組,峰值源/沉電流驅動能力500mA/800mA,主要用在筆記本電腦,LCD監視器的AC/DC適配器,離線電池充電器,消費類電子如STB,DVD,DVDR電源.本文介紹了NCP1219主要特性,功能方框圖,應用電路圖以及通用AC輸入非絕緣6W電表降壓電源參考設計主要特性與指標,電路圖和材料清單.

NCP1219: PWM Controller Featuring Dynamic Self Supply

The NCP1219 represents a new, pin to pin compatible, generation of the successful 7−pin current mode NCP12XX product series. The controller allows for excellent standby power consumption by use of its adjustable skip mode and integrated high voltage startup FET. Internal frequency jittering, ramp compensation, timer−based fault detection and a latch input make this controller an excellent candidate for converters where ruggedness and component cost are the key constraints.

The Dynamic Self Supply (DSS) drastically simplifies the transformer design in avoiding the use of an auxiliary winding to supply the NCP1219. This feature is particularly useful in applications where the output voltage varies during operation (e.g. battery chargers). Due to its high voltage technology, the IC can be directly connected to the high voltage dc rail.

NCP1219主要特性:

• Fixed−Frequency Current−Mode Operation with Ramp Compensation (65 kHz and 100 kHz Options)

• Dynamic Self Supply Eliminates the Need for an Auxiliary Winding

• Timer−Based Fault Protection for Improved Overload Detection

• Cycle Skip Reduces Input Power in Standby Mode

• Latch and Auto−Recovery Overload Protection Options

• Internal High Voltage Startup Circuit

• Accurate Current Limit Detector (±5%)

• Adjustable Skip Level

• Latch Input for Easy Implementation of Overvoltage and Overtemperature Protection

• Frequency Modulation for Softened EMI Signature

• 500 mA/800 mA Peak Source/Sink Current Drive Capability

• Pin to Pin Compatible with the Existing NCP12XX Series

• These Devices are Pb−Free and Halogen Free/BFR Free*

NCP1219典型應用:

• AC−DC Adapters for Notebooks, LCD Monitors

• Offline Battery Chargers

• Consumer Electronic Appliances STB, DVD, DVDR

圖1.NCP1219功能方框圖

圖2.NCP1219應用電路圖

通用AC輸入非絕緣6W電表降壓電源參考設計

This design note describes a simple, low power, off-line, extended universal AC input buck power supply intended for powering utility electric meters or similar industrial equipment or white goods where isolation from the AC mains is not required and low cost and circuit simplicity is essential.

The featured power supply is a simple buck regulator topology utilizing ON Semiconductor’s NCP1219B current mode PWM controller riving an external Dpak MOSFET (Q1). The controller circuitry is ground referenced to the freewheel diode’s cathode terminal which is a switched node. This allows for simple halfwave input rectification and a common AC input to dc output node. Because the NCP1219 controller and its associated circuitry are at a switched node, optocoupler feedback from the NCP431 output sensing amplifier is utilized to avoid regulation inaccuracies typically caused by charge pump and/or bootstrap type sensing schemes. Diode D4 also powers the control circuitry from the output voltage once the converter has started.

The half-wave input rectifier section utilizes a pi-network, split bulk capacitor scheme which provides for both high input transient protection (with optional TVS1) and effective conducted EMI attenuation. The choice of the total bulk capacitance can be selected for the desired output hold-up time during line cycle outages or extreme brownout conditions. Hold-up time along with efficiency and output ripple plots are shown below.

通用AC輸入非絕緣6W電表降壓電源主要指標:

通用AC輸入非絕緣6W電表降壓電源主要特性:

Extended universal AC input range (60 – 300 Vac) with up to 10 watts peak output.

Bulk pi-network filter for conducted EMI attenuation and input transient protection.

AC input to dc output common node.

Inherent over-current protection and optional Z1 over-voltage protection clamp.

Simple, low cost circuitry with off-the-shelf output inductor (L2).

圖3.采用NCP1219B65的6W離線電源電路圖
通用AC輸入非絕緣6W電表降壓電源材料清單(BOM):

詳情請見:
http://www.onsemi.cn/pub_link/Collateral/NCP1219-D.PDF
和
http://www.onsemi.cn/pub_link/Collateral/DN05014-D.PDF