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| 文章來源： 更新時(shí)間：2015/1/27 15:38:00 |
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TI公司的UCC28740是絕緣-反激電源控制器,采用光耦器來提高大負(fù)載的瞬態(tài)響應(yīng),恒流(CC)穩(wěn)壓通過初級邊穩(wěn)壓(PSR)來實(shí)現(xiàn).電流穩(wěn)定度±5%,電壓穩(wěn)定度±1%,器件集成了700V起動(dòng)開關(guān),動(dòng)態(tài)控制工作狀態(tài),支持超低待機(jī)功耗,主要用在AC/DC電源,電動(dòng)自行車,服務(wù)器PSU,低端洗衣機(jī),烘干機(jī),微波爐,太陽能逆變器等.本文介紹了UCC28740主要特性,框圖, 設(shè)計(jì)案例以及85 - 265VAC輸入12V@3A 36W高效適配器參考設(shè)計(jì)主要特性,電路圖和材料清單.
The UCC28740 isolated-flyback power-supply controller provides Constant-Voltage (CV) using an optical coupler to improve transient response to large-load steps. Constant-Current (CC) regulation is accomplished through Primary-side Regulation (PSR) techniques. This device processes information from opto-coupled feedback and an auxiliary flyback winding for precise high-performance control of output voltage and current.
An internal 700-V startup switch, dynamically-controlled operating states, and a tailored modulation profile support ultra-low standby power without sacrificing startup time or output transient response.
Control algorithms in the UCC28740 allow operating efficiencies to meet or exceed applicable standards. The drive output interfaces to a MOSFET power switch. Discontinuous conduction mode (DCM) with valley-switching reduces switching losses. Modulation of switching frequency and primary current-peak amplitude (FM and AM) keeps the conversion efficiency high across the entire load and line ranges.
The controller has a maximum switching frequency of 100 kHz and always maintains control of the peak-primary current in the transformer. Protection features keep primary and secondary component stresses in check. A minimum switching frequency of 170 Hz facilitates the achievement of less than 10-mW no-load power.
UCC28740主要特性:
Less than 10-mW No-Load Power Capability
Opto-Coupled Feedback for CV, and Primary-Side
Regulation (PSR) for CC
Enables ±1% Voltage Regulation and ±5% Current
Regulation Across Line and Load
700-V Startup Switch
100-kHz Maximum Switching Frequency Enables
High-Power-Density Charger Designs
Resonant-Ring Valley-Switching Operation for
Highest Overall Efficiency
Frequency Dithering to Ease EMI Compliance
Clamped Gate-Drive Output for MOSFET
Overvoltage, Low-Line, and Overcurrent
Protection Functions
SOIC-7 Package
UCC28740應(yīng)用:
AC/DC Power Supply - Dual Analog Controller
E-Bike
Power Supply: AC/DC, Isolated, no PFC,< 90W
Server: PSU
Washing Machine: Low-End
Clothes Washer & Dryer
Microwave Oven
Power Supply: AC/DC, Isolated, w/ PFC,> 90W
Solar Inverters
圖1. UCC28740框圖
圖2. UCC28740簡化應(yīng)用電路圖
圖3. UCC28740設(shè)計(jì)案例
85 - 265VAC輸入12V@3A 36W高效適配器參考設(shè)計(jì)
This reference design provides an isolated 12V/36W output from a universal AC input range with over 89% peak efficiency. The UCC24610 synchronous rectifier controller and CSD19531Q5A FET reduce the rectifier loss and provide high efficiency with a minimal increase in cost. The UCC28740 flyback controller uses a combination of peak current modulation and frequency modulation to maintain excellent efficiency at lighter loads and minimize no load power consumption. The current regulation feature of the UCC28740 provides accurate current limit protection. This compact design consumes a volume of only 2.0" x 2.0" x 0.75".
36W高效適配器參考設(shè)計(jì)主要特性:
Compact AC/DC adaptor design (2.0" x 2.0" x 0.75")
Synchronous rectification for high efficiency (>89% peak, 88.7% average)
Accurate current limiting
Consumes less than 150mW power at no load to qualify for 4-star EC IPP Mobile device charger rating
Less than 150ms start-up time at full-load
圖4.36W高效適配器參考設(shè)計(jì)外形圖
圖5.36W高效適配器參考設(shè)計(jì)電路圖
36W高效適配器參考設(shè)計(jì)材料清單:
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