Cree has introduced two new high-voltage (HV) LEDs, the XLamp XM-L and XT-E, that the company says can boost driver efficiency by 10-20% in small retrofit lamps. The company also announced a new version of the XLamp MT-G LED for solid-state-lighting (SSL) applications that's 10% brighter than predecessors with the new LEDs delivering 1670 lm. Osram, meanwhile, launched new orange, yellow, and red Oslon SSL LEDs that can deliver 20% more light than predecessors.
The Cree XM-L and XT-E LEDs target small retrofit-lamp application such as B10 candelabra lamps along with E17 and GU10 lamps. The HV-LEDs will deliver efficiency and thermal advantages in such lamps that are severely space constrained with limited options for cooling.
The LEDs are packaged and sold as discrete components, but in reality are built using an array of 16 very-small die. The XT-E is 3.45 mm on a side and the XM-L is 5 mm on a side. According to product marketing manager Paul Scheidt, target applications such as B10 lamps will use one or perhaps two of the LEDs.
By connecting the array in series, Cree was able to boost the forward voltage to 48V. According to Scheidt the higher voltage improves efficiency because the driver doesn't have to drop the line voltage down to the 4V level that would be required in a single emitter that's equivalent in size and lumen output to the array.
In the simplest case where a rectifier diode drives an LED, the system efficiency goes from 87.5% with a single emitter to 98% with the HV array. Cree says that in actual products the driver efficiency advantage may reach 20% while also enabling smaller, lower-cost drivers that run 10% cooler .
"Maximizing the LED voltage, as Cree has done in the new high-voltage XM-L and XT-E LEDs, is a very effective way to minimize current through the LED driver output rectifier," said Peter Vaughan, director of applications engineering at driver-IC manufacturer Power Integrations, Inc. "This can reduce losses and heat dissipation in the driver and increase the overall system luminous efficacy by several percentage points."
The concept of HV-LEDs and the efficiency advantage is not new. Indeed Cree offers a number of HV-LEDs in larger arrays. But Scheidt said, "Most HV-LEDs are efficient and large or small and inefficient." Scheidt showed efficacy graphs for the new LEDs compared to unnamed competitive products that would indicate a roughly 20-40 lm/W advantage for the new LEDs.
Cree says the LEDs will enable the first competitive SSL replacements for small lamps and received an endorsement from one customer. "The XLamp XM-L High-Voltage LED eliminates the trade-off between size and efficacy, allowing us to take advantage of the efficacy of high-voltage drivers," said Ken Chakravarti, chief technology officer, Ledzworld. "This translates to more efficient, better and more cost-effective small LED lamps and luminaires such as the B10 replacement lamp for our customers."
沒有留言:
張貼留言