</a>LED" title="LED">LED" title="LED">LEDAC02是高性能离线LED驱动器，AC离线输入从80V到277VAC，输出功率高达25W，调光范围从2%到100%，智能墙壁调光器检测，主要用在可调光的离线LED驱动器，可调光的LED替代灯以及可调光的LED光源。本文介绍了CY8CLEDAC02主要特性，逻辑方框图，简化的应用电路图以及12W 220VAC输入调光LED驱动器参考设计指标，电路图,变压器指标与电路图以及材料清单,PCB元件布局图。

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 10uA)

■ 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应用:

❐ Dimmable offline LED driver

❐ Dimmable LED replacement lamps

❐ Dimmable LED luminaires

图1.CY8CLEDAC02逻辑框图

图2.CY8CLEDAC02简化的应用框图

A55 220VAC 12W调光LED驱动器参考设计

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.


图3.12W LED驱动器参考设计外形图
LED驱动器参考设计指标:


图4. 12W LED驱动器参考设计电路图

LED驱动器参考设计材料清单:


变压器指标:

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

图5.变压器尺寸和电路图

图6.参考设计PCB元件布局图(顶层)
详情请见:
http://www.cypress.com/?docID=24621
和
http://www.cypress.com/?docID=30594