Industry’s fastest write and rewrite speeds

National Semiconductor Corporation has today launched the LMH6533, its newest laser diode driver (LDD) for use in optical pickup units (OPUs).

National Semiconductor Corporation has today launched its newest laser diode driver (LDD) for use in optical pickup units (OPUs).

The LMH6533 – designed for combination DVD/CD recorder optical storage devices used in desktop, notebook and consumer DVD video recorders – is said to have extremely fast switching rates and very low output current noise with low power consumption.

According to National Semiconductor, the reduced power consumption provides better heat dissipation in the system, while the low noise allows the fastest read times for optical disk drives.

“National’s LMH6533 laser diode driver’s fast switching rates of 0.5 nanoseconds allow us to achieve the industry’s fastest write and rewrite speeds of 16x write and 8x rewrite capability,” said Erroll Dietz, vice president of National’s Amplifier product group.

Dietz added: “We continue to develop laser diode drivers for the red laser system requirements for current DVD drives. We are also developing laser diode drivers for the next-generation DVD blue laser systems, which will make it possible to write 25 GB of data on each side of a DVD.”

By integrating the low voltage differential signalling (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.

National’s VIP10C process technology provides a very fast switching rate of 0.5ns and noise levels of 0.5nA per square root hertz, enabling the fastest read, write and rewrite times for optical recording.

National’s LMH6533 laser diode driver 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 minimising noise and cross-talk. The device provides one 300mA and two 150mA write channels, plus a 150mA read channel. Additionally, it minimises electromagnetic interference (EMI), allowing disk drive manufacturers to develop devices without the extra cost of shielding.

National’s LMH6533 is available now in LLP-28 packaging and is priced at $0.85 in high-volume quantities.