120VAC offline LED driver board ADM00766 and LED load board ADM00767 main features (Figure)

Microchip's CL88020 is an off-line LED Driver with an input voltage of 120VAC and 8.5W of LED power. The device includes the CL88020 LED driver, six resistors and a bridge rectifier. It has programmable overtemperature protection, allowing THD to be thick and optional to reduce light load output. Ripple, using only one external ceramic storage capacitor, TRIAC dimming compatible, mainly used in LED lights and LED lighting fixtures. This article describes the main features of the CL88020, block diagrams and typical application circuits, as well as 120VAC offline LED driver board ADM00766 and LED load board ADM00767 main features, circuit diagrams, bill of materials and PCB design drawings.

The CL88020 LED Driver Integrated Circuit (IC) is anoff-line sequenTIal linear LED driver designed to provide 8.5W of LED power from a 120 VAC nominal inputvoltage.

CL88020 is designed to drive a long string of inexpensive, low-current LEDs directly from the AC mains. Abasic driver circuit consists of Microchip Technology Inc.'s CL88020 LED driver IC, six resistors and a bridgerecTIfier. Two to four addiTIonal components are opTIonalfor various Level of transient protection, also with a low-cost NTC to assure remote overtemperature protection (OTP). No capacitors, EMI filters, or power factorcorrection circuits are needed unless the corresponding modified light output ripple feature is desired.

A string of series/parallel LEDs is tapped at four locations. Four linear current regulators sink current at eachtap through a single control point and are sequentiallyturned on and off. High efficiency is achieved by shuttingoff upstream regulators when downstream regulatorsachieve regulation. Input current easier than trying to control multiple currentpaths, thus tracking the input sine wave voltage.

CL88020 uses a self-commutation techniqueusing only the tap currents themselves; this techniqueinherently provides smooth transitions from one regulator to the next, without relying on tap voltages or therectified AC to coordinate the transitions.

Key features of CL88020:

• Optimized for 120 VAC Nominal Input Voltage
- 120VAC ± 15% input voltage
• Targeted for 8.5W Output Power
• Programmable Overtemperature Protection
- Provides Gradual Reduction in Light Outputwith Increasing Temperature
• Active Line Regulation
- Provides Fairly Constant Output Power overVariations in AC Line Voltage
- Typical Line Regulation of –12% to +0%
• Four Taps with Two Current Set Resistors
- Allows Optimization of THD
• Optional Reduced Light Output Ripple
- Provides Continuous Power to the LED
- Eliminates Strobing
- Uses an External Ceramic Storage Capacitor
• TRIAC Dimmer Compatible
• Available in a Thermally Enhanced 8-Lead SOICPackage with Heat Slug
- Larger Creepage Distances between HighVoltage and Low Voltage Pins

CL88020 120VAC Offline LED Driver Board ADM00766 and LED Load Board ADM00767 The CL88020 120 VAC Offline LED Driver Evaluation Board is a complete solution consisting of an LED Driver (ADM00766) and an LED Load Board (ADM00767) powered directly from the 120VAC line and based on Microchip Technology's CL88020 sequential linear LED driver. The application achieves efficient operation without using anymagnetics or conventional switching techniques and is a flexible solution that allows users to design and to test their own LED Load solution. The included LED Load ismade with 10 LEDs. Since no high frequencies Are present, it exhibits inherently lowconducted and radiated EMI without needing input filters or shielding. Because the current through the LEDs follows the AC input voltage, PFC circuitry is also not needed.

The CL88020 is inherently compatible with both leading-edge and trailing-edge dimmers,with no need for special circuitry to detect and respond to them.The LED Load is provided on a double-layer 60 mm diameter FR4 PCB (0.6 mm thick)mounted The LED Driver PCB (ADM00766) is made on 1.6 mm standard double-layer FR4. The kit includes an 8-wire flat cable to connect the LED Driver Board to the LED Load, and a black anodized pin Fin Heat Sink with double-sidedadhesive thermal tape necessary to mount the LED Load Board on it. All circuitry andhardware is provided, along with transient protection and overtemperature protection.Just plug into a 120 VAC outlet (50 Hz or 60 Hz) to get started .

LED driver evaluation board ADM00766 main features:

• Input Voltage: 120 Vrms +/-15%, 50/60 Hz
• Typical Output Capability: up to 130 mA
• Efficiency: Over 83%
• Max Output Power: 8.5W (depends on the cooling provided)
LED load board ADM00767 main features:
• Contains 10 LEDs (GW P9LR31.EM) grouped in 4 taps
• An 8-wire flat cable input connector
• One NTC for overtemperature protection
The CL88020 120VAC Offline LED Evaluation Board Kit includes:
• CL88020 LED Driver Evaluation Board (ADM00766)
• 8-wire interconnection flat cable
• 4 nylon stand-offs with corresponding screw
• Important Information Sheet
CL88020LED load board ADM00767 includes:
• CL88020 LED Load Board (ADM00767)
• LED Load pin fin heat sink
• Thermal double-sided adhesive tape
• Important Information Sheet