 2015 Microchip Technology Inc.

DS20005357A-page 1

CL8800

Features

• Minimal component count (base config: CL8800 +

6 resistors + diode bridge)

• No magnetics, no capacitors

• Up to 7.5W output (13W w/ heat sink)

• >110Lm/W using efficient LEDs

• 85% typical electrical efficiency

• >0.95 power factor

• <20% THD line current

• Low conducted EMI w/o filters

• 85% LED luminous utilization

• Phase dimmer compatible with an RC network

Applications

• Fluorescent tube retrofit

• Incandescent & CFL bulb replacement

• General LED lighting

Description

CL8800 is designed to drive a long string of inexpen-

sive, low-current LEDs directly from the AC mains. A

basic driver circuit consists of CL8800, six resistors,

and a bridge rectifier. Two to four additional compo-

nents are optional for various levels of transient protec-

tion. No capacitors, EMI filters, or power factor

correction circuits are needed.

A string of series/parallel LEDs is tapped at six loca-

tions. Six linear current regulators sink current at each

tap and are sequentially turned on and off. Thereby

tracking the input sine wave voltage. Voltage across

each regulator is minimized when conducting, provid-

ing high efficiency. Output current at each tap is individ-

ually resistor-adjustable. Cross-regulation, as the

CL8800 switches from one regulator to another, pro-

vides smooth transitions. The current waveform can be

tailored to optimize for input voltage range, line/load

regulation, output power/current, efficiency, power fac-

tor, THD, dimmer compatibility, and LED utilization.

With the addition of an RC network, the driver is com-

patible with phase dimming.

Sequential Linear LED Driver