IC drives long LED strings

-July 12, 2017

Microchip’s CL88020 sequential linear LED driver for offline lighting drives a long string of low-current LEDs directly from a 120 VAC line input. The CL88020 driver enables the creation of reliable and compact LED lighting applications by offering high power factor without the need for the switch-mode power conversion typically required for LED lighting design.

Intended to minimize driver circuit component count, the CL88020 allows for a single-layer PCB design. Just six resistors and a bridge rectifier are required to form a basic driver circuit capable of providing 8.5 W of LED power. Two to four additional components are optional to achieve various levels of transient protection, while an NTC thermistor ensures remote overtemperature protection. No capacitors, EMI filters, or power-factor circuits are required, unless reduced output ripple is desired.

A string of series/parallel LEDs is tapped at four locations. Four linear current regulators sink current at each tap through a single control point and are sequentially turned on and off. High efficiency is achieved by shutting off upstream regulators when downstream regulators achieve regulation.

Housed in an SOIC-8 package, the CL88020 LED driver is available for sampling and in volume production with prices starting at $0.93 each in lots of 10,000 units.

CL88020 product page

Microchip Technology, www.microchip.com

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