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Cypress 公司的CY8CLEDAC02是高性能離線LED驅動器，AC離線輸入從80V到277VAC，輸出功率高達25W，調光范圍從2%到100%，智能墻壁調光器檢測，主要用在可調光的離線LED驅動器，可調光的LED替代燈以及可調光的LED光源。本文介紹了CY8CLEDAC02主要特性，邏輯方框圖，簡化的應用電路圖以及12W 220VAC輸入調光LED驅動器參考設計指標，電路圖,變壓器指標與電路圖以及材料清單,PCB元件布局圖。 The CY8CLEDAC02 is a high performance offline LED driver, designed to interface directly with most conventional phase cut based wall dimmers. The device uses proprietary digital control technology to provide automatic detection of dimmer type (leading or trailing edge). It automatically generates dimming signals for LED loads and has the ability to dim down to 2 percent. It modulates LED brightness using a linear dimming scheme and switches to a pulse width modulation (PWM) based dimming scheme for output current levels lower than 20 percent of the full load current. In PWM mode optimized dimming frequencies in the range of 900 Hz result in zero visible flicker.At the heart of a CY8CLEDAC02 based system is the chopping circuit which provides the load necessary to enable correct wall dimmer operation. It also improves PF when there is no dimmer on the line. The devices’ proprietary primary side sensing enables tight LED current regulation and eliminates the need for secondary feedback circuitry. No opto-couplers are necessary to meet UL isolation requirements; enabling flyback conversion with automatic isolation. The CY8CLEDAC02 operates in quasi-resonant mode to achieve high efficiency. This mode of operation helps minimize external component count and simplifies EMI design, lowering the total bill of material cost. The device’s cycle-by-cycle adaptive digital regulation uses critical discontinuous conduction mode (CDCM) when driving LED loads. The control algorithm for cycle-by-cycle regulation has internal compensation for guaranteed system phase and gain margins; requiring no external components for loop compensation. The CY8CLEDAC02 has full featured circuit protection not normally available with other primary-side control solutions. The built-in protection includes output overvoltage protection, output short circuit protection, overtemperature protection, current-sense resistor short protection, and peak current limit protection. It also enables automatic LED brightness adjustment to compensate for temperature drift by simply connecting a NTC resistor to the VT pin. CY8CLEDAC02主要特性: ■ AC offline input range from 80 to 277 VAC ■ Up to 25 W output power range ■ Intelligent wall dimmer detection: ❐ Leading edge (R, RL) dimmers ❐ Trailing edge (RC, RLC) dimmers ❐ No dimmer ■ Wide dimming range from 2 to 100 percent ■ Resonant control to achieve high efficiency (85 percent without dimmer) ■ Meets harmonic requirement with high power factor (0.7 without dimmer) ■ Primary-side sensing eliminates opto-isolators ■ Tight LED current regulation (typically < + 2.5 percent) ■ Low startup current (typically 10uA) ■ Low startup time (typically 0.5 s with active startup) ■ Multiple protection features: ❐ Output overvoltage protection (OOVP) ❐ Output short circuit protection (OSCP) ❐ Overtemperature protection (OTP) ❐ Current-sense resistor short protection (CSSP) ❐ Peak current limit protection (PCLP) ❐ Single-point fault protection CY8CLEDAC02應用: ❐ Dimmable offline LED driver ❐ Dimmable LED replacement lamps ❐ Dimmable LED luminaires 
圖1.CY8CLEDAC02邏輯框圖
圖2.CY8CLEDAC02簡化的應用框圖 A55 220VAC 12W調光LED驅動器參考設計 This document describes a highline 12 W dimmable LED driver reference design using the CY8CLEDAC02 AC-DC power controller device. This design is capable of driving a string of LEDs with a typical forward voltage of 27 V at 350 mA. The CY8CLEDAC02 is a high-performance offline LED driver, designed to interface directly with most conventional phase-cut based wall dimmers. The device uses proprietary digital control technology to provide automatic detection of dimmer type (leading or trailing edge). It automatically generates dimming signals for LED loads and has the ability to dim down to 2 percent.
圖3.12W LED驅動器參考設計外形圖 LED驅動器參考設計指標:
圖4. 12W LED驅動器參考設計電路圖 LED驅動器參考設計材料清單:
變壓器指標: Electrical specifications Primary inductance: 2360 μH at 10 kHz Primary leakage inductance: Renco Electronics ≤ 44 μH at 10 kHz Würth Elektronik ≤ 25 μH at 10 kHz Peak primary current: 380 mA Peak secondary voltage: 29 V Peak secondary current: 350 mA Primary-to-secondary turns ratio: 5-to-1 Secondary-to-auxiliary turns ratio: 2-to-1 Flyback switching frequency: 120 kHz to 150 kHz Materials Core: EP13 (Ferrite material TDK PC40 or equivalent) Bobbin: EP13 Magnet wire: Type 2UEW Triple insulated wire: TEX-E or equivalent Layer insulation tape: 3M1350f-1 or equivalent Teflon sleeve
圖5.變壓器尺寸和電路圖
圖6.參考設計PCB元件布局圖(頂層) 詳情請見: http://www.cypress.com/?docID=24621 和 http://www.cypress.com/?docID=30594 |
