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National LDD a perfect fit for OPUs

Posted: 20 Aug 2004 ?? ?Print Version ?Bookmark and Share

Keywords:national semiconductor? laser diode driver? ldd? optical pickup unit? opu?

National Semiconductor launched its newest laser diode driver (LDD) for use in optical pickup units (OPUs). The LMH6533 has extremely fast switching rates and very low output current noise with low power consumption. The reduced power consumption provides better heat dissipation in the system, while the low noise allows the fastest read times for optical disk drives. The LMH6533 is designed for combination DVD/CD recorder optical storage devices used in desktop, notebook and consumer DVD video recorders.

"National's LMH6533 laser diode driver's fast switching rates of 0.5ns allow us to achieve the industry's fastest write and rewrite speeds of 16x write and 8x rewrite capability," shared Erroll Dietz, VP of National's Amplifier product group. "We continue to develop LDDs for the red laser system requirements for current DVD drives. We are also developing LDDs for the next-generation DVD blue laser systems, which will make it possible to write 25GB of data on each side of a DVD."

The company's new product allows OPU manufacturers to provide consumers with the highest-performance DVD/CD recorders on the market. National's expanding portfolio of LDDs leverages its unique capabilities in high-speed analog amplifiers, low voltage differential signaling (LVDS) technologies, LLP chip-scale package technology and innovative VIP10 manufacturing process.

By integrating the LVDS interface into the driver, National addresses the high speed requirements of driving the signal from the controller chip to the OPU. The LVDS interface also reduces overall system costs for optical storage device manufacturers by keeping the write strategy digital circuitry on the controller chipset rather than integrating it into the laser diode driver.

The LMH6533 contains two high-current outputs for reading and writing DVD (650nm) or CD (780nm) lasers. It achieves read, write and erase functions through four separate switched current channels. The LVDS interface delivers DVD write speeds of 16x and higher while minimizing noise and cross-talk. The device provides one 300mA and two 150mA write channels, plus a 150mA read channel. Additionally, it minimizes EMI, allowing disk drive manufacturers to develop devices without the extra cost of shielding.

The VIP10C technology

The device is the latest LDD created using the VIP10C process technology, which provides a switching rate of 0.5ns and noise levels of 0.5nA per square root hertz, enabling one of the fastest read, write and rewrite times for optical recording.

Developed in National's wafer fabrication site in Arlington, Texas, the VIP10C is a high-speed, dielectrically isolated, complementary BiCMOS process that utilizes deep trench technology on a bonded wafer for complete dielectric isolation and optimal high-speed amplifier performance. According to the company, this process technology allows them to design the most power-efficient, performance-oriented high-speed amplifiers on the market today.

The LMH6533 is available in LLP-28 packaging and is priced at 85 cents in high-volume quantities.

- Paul O'Shea


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