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,調光效率從2%到100%,主要用在可調光的離線LED驅動器,LED替代燈以及LED照明.本文介紹CY8CLEDAC02主要特性,方框圖, 簡化和典型的應用電路圖,以及采用CY8CLEDAC02的 220VAC 17W可調光LED驅動器參考設計系統指標,電路圖,材料清單和變壓器指標.

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%. It modulates LED brightness using a linear dimming scheme and switches to a PWM based dimming scheme for output current levels lower than 20% 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 (OOVP), output short circuit protection (OSCP), overtemperature protection (OTP), current-sense resistor short protection (CSSP), and peak current limit protection (PCLP). 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 25W 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%

■ Resonant control to achieve high efficiency (85% 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%)

■ Low startup current (typically 10??A)

■ Low startup time (typically 0.5s 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邏輯方框圖

圖2.CY8CLEDAC02簡化應用電路圖


圖3.CY8CLEDAC02典型應用電路圖

采用CY8CLEDAC02的17W調光LED驅動器參考設計

HighLine 17 W Dimmable LED Driver using CY8CLEDAC02 Reference Design Guide

This document describes a 17W dimmable LED driver reference design using the CY8CLEDAC02 AC-DC power controller device. This reference design is capable of driving eight white LEDs (typical load voltage of 25 V) at 530 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%.

參考設計系統指標:



圖4.17W調光LED驅動器參考設計外形圖

圖5.17W調光LED驅動器參考設計電路圖
17W調光LED驅動器參考設計材料清單(BOM):




變壓器指標:

The transformer is one of the most important components in this LED driver circuit. As explained in previous sections, in addition to the two standard windings, typical flyback converter transformers incorporate a third winding. In this circuit, it is used to provide voltage sensing for output voltage regulation and no-load protection by the CY8CLEDAC02 device. This winding, called the bias or auxiliary winding, also provides supply voltage (VCC) to the CY8CLEDAC02.

The specifications of the transformer for this reference design are as follows:

Electrical specifications

Primary inductance = 1200 μH at 10 kHz

Primary leakage inductance ≤ 20 μH at 10 kHz

Materials

Core: EF2011 (Ferrite material TDK PC40 or equivalent)

Bobbin: EF2011

Magnet wires: Type 2UEW

Layer insulation tape: 3M1298 or equivalent

詳情請見:
http://www.cypress.com/?docID=21407
和
http://www.cypress.com/?docID=23309