CL8800 & CL8801 Drive Long Strings of LEDs Directly from AC Mains
Supertex introduced CL8800 and CL8801, sequential, linear LED drivers designed to drive long strings of low cost, low current LEDs in solid-state replacements for fluorescent tubes, incandescent bulbs and CFL bulbs. Both ICs minimize driver circuit component counts, requiring just four or six resistors and a diode bridge in addition to the IC. Two to four additional components in the circuit provide transient protection, and neither capacitors nor magnetic components are required. Because the ICs are multi-stage linear current regulators, there are no high frequency switching currents and, thus, no need for a front-end EMI filter. CL8800 is intended for 230VAC input, while CL8801 is for 120VAC input. Luminous efficiencies of greater than 115lm/W are achievable with both ICs.
CL8800 has six current regulator outputs and CL8801 has four. These outputs tap a string of series parallel LEDs, and the regulators sink current at each tap and are sequentially turned on and off automatically, tracking the input sine wave voltage. Voltage across each regulator is minimized when conducting, providing typical efficiency of greater than 90%. Output current at each tap is individually resistor-adjustable. Cross regulation, as the IC switches from one regulator to another, provides smooth transitions. The current waveforms of both ICs can be tailored to optimize for input voltage range, line/load regulation, output power/current, efficiency, power factor, THD, dimmer compatibility and LED utilization. Both ICs are compatible with phase dimming with the addition of an RC network.
Typical Application Circuit
CL8800 and CL8801 are available in 40- and 33-lead QFN packages (CL8800K6-G, CL8801K6-G, CL8800K63-G, CL8801K63-G, respectively). The parts are RoHS compliant. Samples of CL8800K6-G and CL8801K6-G are available from stock. Lead-time for production quantities of CL8800K6-G and CL8801K6-G is 4-6 weeks. Consult factory for samples and lead times of CL8800K63-G and CL8801K63-G. Pricing is US$2.38 each for all parts in 1K quantities.
