Date: 13/06/2012

Non-dimmable flyback driver from NXP uses smart digital control for better accuracy

NXP Semiconductors N.V. has introduced the SSL21101 LED driver chip from the family of GreenChip. The SSL21101 LED driver IC is developed using the smart digital control (SDC) technology. The device is designed in a compact package to deliver better and accurate system performance. This chip is suitable for non-dimmable, high-performance LED applications up to 15W.

"Smart Digital Control is an important step forward for LED lighting, opening new possibilities as we introduce optimized algorithms for very high performance levels while reducing system costs," said Stephane Curral, vice president and general manager, power and lighting solutions business line, NXP Semiconductors. "By offering a digital core within a traditional analog system, we're making it easy for engineers to fine-tune and achieve the right balance between efficiency, current regulation and system cost for their specific LED designs - with more flexibility compared to pure analog solutions."

The SSL21101 is a single-stage solution designed to drive LED devices in flyback or buck-boost configurations with high efficiency and with accurate control of the output current. The SDC feature offers two modes optimized for specific regional regulatory requirements. In high power factor mode, the PF rating is higher than 0.95 and the total harmonic distortion (THD) is limited to under 20%. The low ripple mode lowers the LED current ripple below 1% and makes it possible to use smaller electrolytic capacitors.

The SSL21101 includes a high-voltage power switch and a circuit that enables start-up directly from the rectified mains voltage. The device is priced at US $1.30 for a complete system eBOM excluding LEDs.

Features:
1. Non-dimmable LED driver power: 15W from 100V to 230V (universal mains)
2. Integrated 700V MOSFET
3. Efficiency: 90%
4. Primary side sensing (no optocoupler required)
5. True current source behaviour, independent of mains voltage, LED voltage, temperature and coil variations
6. Current accuracy: 3%
7. Set of internal protections such as short-winding protection, internal over-temperature protection (OTP), LED short protection, LED open protection, and undervoltage lockout protection (UVLO)
8. NTC input pin to limit the maximum LED temperature
9. SO14 package

The driver chip for non-dimmable LED applications is now in volume production. The SDC products addressing dimmable LED applications are currently under development.
Data sheet: http://www.nxp.com/documents/data_sheet/SSL21101T.pdf