Cypress 公司的CY8CLEDAC02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,调光效率从2%到100%,主要用在可调光的离线LED驱动器,LED替代灯以及LED照明.本文介绍CY8CLEDAC02主要特性,方框图, 简化和典型的应用电路图,以及采用CY8CLEDAC02的 220VAC 17W可调光LED驱动器参考设计系统指标,电路图,材料清单和变压器指标.
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 10A)
■ 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应用:
❐ Dimmable offline LED driver
❐ Dimmable LED replacement lamps
❐ Dimmable LED luminaires
图1.CY8CLEDAC02逻辑方框图
图2.CY8CLEDAC02简化应用电路图
图3.CY8CLEDAC02典型应用电路图
采用CY8CLEDAC02的17W调光LED驱动器参考设计
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%.
参考设计系统指标:
图4.17W调光LED驱动器参考设计外形图
图5.17W调光LED驱动器参考设计电路图
17W调光LED驱动器参考设计材料清单(BOM):
变压器指标:
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
详情请见:
http://www.cypress.com/?docID=21407
和
http://www.cypress.com/?docID=23309
