基于CY8CLEDAC02的17W LED驅動器設計方案
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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
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