Power Management I Product News Emerson adds 25 Watt series to its portfolio of power supplies for LED lighting
Emerson Network Power has unveiled a new series of high efficiency power supplies for LED lighting. The LDS25 series joins the company's LDS70 series of 70 watt products for this fast- growing market. These off-the-shelf pre-certified power solutions will enable original equipment manufacturers and system installers to reduce their time-to-market significantly using reliable LED lighting drivers.
The new series of 25 watt LED power supplies have an input range of 120 to 277 Vac and can deliver up to 700 mA at 36 Vdc. Constant current and constant voltage output modes accommodate different LED application requirements. Constant current mode operates from 36 V down to 26 V, while constant voltage mode operates with load currents from 300 to 700 mA or to the programmed current limit level
- which can be set by a single resistor to any value within this range. Alternatively, the output current can be user adjusted over its full 0 to 700 mA range by an IEC 60929 compliant dimming function, controlled by a standard 0 to 10 V signal.
Active power factor correction enables the LDS25 to achieve a power factor of at least 0.9 and they have a high conversion efficiency of 86 percent typical. They are rated for operation over an ambient temperature range of minus 30 to 60 degrees Celsius or a case temperature range of minus 30 to 90 degree Celsius, with no need for forced air cooling. They are suitable for a wide range of indoor applications and are available in open-frame and IP20 rated cased versions for customer flexibility. The open frame model has a very small footprint of 5.8 x 1.6
inches (147 x 42 mm) and a height of just 1.1 inches (28 mm), while the IP20 cased model is 6.87 x 1.80 inches (174.5 x 45.6 mm) and is 1.26 inches (32 mm) high. The LDS25 series fully comply with the CISPR 15 requirement for EMI and meet FCC part 15 conducted noise standards. They are comprehensively protected against short- circuit, overvoltage and overtemperature conditions and additional features include hot-wiring protection, which automatically limits the rate of increase of output current to prevent damage to the LED and driver circuits.
Emerson Network Power |
www.EmersonNetworkPower.com
H-Bridge transformer driver to enable simple and flexible isolated DC-DC designs
Maxim Integrated Products has unveiled the MAX13256, an H-bridge transformer driver with a wide input-voltage range for isolated power supplies. A simple solution it will enable engineers to quickly design a efficient (up to 90%) isolated DC-DC converters. The MAX13256 drives a transformer's primary coil with up to 300mA of current from an 8V to 36V DC supply which can deliver up to 10W of isolated power. Users can choose their own transformer winding ratio which defines the output voltage, thus allowing the selection of virtually any isolated output voltage. This robust supply range eliminates external voltage regulation. Integrated protection features prevent system-level failures. By eliminating 16 discrete components, the MAX13256 simplifies BOM complexity and reduces footprint with high integration in a tiny TDFN package. With all these capabilities, the MAX13256 driver is a simple way to create isolated power supplies in smart grid metering
applications, and industrial and medical equipment.
Smart grid applications utilising wired interface communications require isolated power to protect against high-voltage mains that can damage both the installer and power meter's internal electronics. The isolated power is typically generated with a transformer and discrete components which increase the solution size and add cost. The MAX13256 drives the transformer that acts as the additional form of isolation from high-voltage mains. A smart grid has different requirements for input voltage and output power that vary based on the type of interface used to communicate with the smart meter. The MAX13256's wide 8V to 36V input voltage range addresses these diverse power-supply input requirements. It also eliminates external voltage regulation, and enables flexible transformer options to satisfy a wide range of power output requirements.
The MAX13256 also integrates protection
features that prevent system-level failures. Adjustable current limiting allows indirect limiting of secondary-side load currents. An overcurrent limit is set by an external resistor over the 215mA to 650mA (typ) range. An active-low FAULT output asserts when the device detects an overtemperature or overcurrent condition. This integrated thermal and short-circuit protection ensures safe operation and reduces both cost and PCB space over discrete solutions. Highly integrated H-bridge and transformer modules are typically more expensive solutions that are limited to providing customers with system optimized isolated output voltages. For applications requiring a simple low-cost approach for nonregulated DC-DC isolation, the MAX13256 is an ideal fit. The efficiency of the MAX13256 (up to 90%)
helps reduce heat in applications where space is premium. In addition, the device features a low-
power mode to reduce the overall supply current to 0.65mA (typ) when the driver is not in use. The MAX13256 is available in a 10-pin TDFN and is specified over the -40°C to +125°C automotive temperature range.
Maxim Integrated Products |
www.maxim-ic.com
42 September 2011
Components in Electronics
www.cieonline.co.uk
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