Taking a look at the lighting side of the power market, International Rectifier introduced its IRS2153D, an electronic ballast IC for fluorescent lamps. In addition to being leadfree, the 600V self-oscillating half-bridge IC includes an internal bootstrap diode to simplify circuits. It’s also designed to increase efficiency and performance over older, less-efficient self-oscillating bipolar transistor-based solutions.
The IRS2153D’s oscillator frequency precision of 3%, helps to optimise external component selection for uniform lamp brightness during manufacturing. A preheat feature, which sets the correct preheat frequency for the correct duration (thus helping to maximise lamp life), can be easily realised externally.
The IC includes 2V undervoltage lockout hysteresis for more robust ballast circuits and prevents unwanted shutdown when there are momentary transients. In addition, an undervoltage lockout circuit ensures that the high-side floating voltage correctly switches the high-side gate driver output.
PoE Device Merges Analogue, Digital, And Power
Switching gears in the ever-evolving power arena, a joint development between PowerDsine and Freescale has borne fruit with the PD64004A 4-Channel Power over Ethernet Manager IC. The four-port PD64004A joins the 12-port PD64012 and other current PD64004 solutions. One particularly smart aspect of this new chip, which uses Freescale’s SMARTMOS8 technology, is that it integrates power, analogue, and advanced digital logic functions into one device. It’s optimised for use in low-port count Ethernet switches, SOHO routers, and midspans, allowing for next-generation network devices to share power and data over the same cable.
The chip is designed to minimise the number of external components required and to reduce overall system costs. Capable of operating under a switch ambient temperature range of –40 to +85C, the PD64004A simplifies the router and switch vendor’s thermal design tasks. This feature will particularly benefit those industrial systems targeted for industrial use. Moving to 1- sense resistors, the PD64004A reduces total thermal dissipation and eases system design. The chip now supports fully automated operation and power management, eliminating the need for microcontrollers.
Special pins dedicated for total setup allow the device to be truly stand-alone. Up to eight PD64004A managers can cooperate automatically to provide up to 32 ports of PoE at the lowest implementation costs. The device fully complies with the IEEE 802.3af-2003 standard, and works with pre-standard proprietary solutions.
White LED Drivers Eye New Colour LCD Panels For Portables
Toshiba Electronics Europe expanded its constant-current white LED-driver product line with a compact dc-dc converter IC for powering multi-segment white LEDs. These drivers are used to backlight new, larger colour LCD panels in small portable devices, including cell phones and PDAs. A single device drives from two to eight LEDs in series. High output power allows for up to 800mW LED loading.
MOSFET driver ICs have flexible gate drive levels
Vishay Intertechnology developed new high-speed, half-bridge MOSFET driver ICs that provide flexible gate-drive levels. The company claims they will optimise efficiency, reduce component count, and minimise expense in high-frequency, highcurrent, dc-dc synchronous rectifier buck power supplies.
The MOSFET drivers (the SiP41109 and SiP41110) operate with external n-channel MOSFETs. They’re designed to provide gate-drive voltages of 8 or 12V, operate at switching frequencies up to 1 MHz, and function in 5 to 48V systems (e.g., power converters, industrial equipment). The high-side driver of each device features an internal bootstrap diode to reduce external component count.