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Zarlink LDDs provide 'industry-leading performance'

Posted: 29 Oct 2004 ?? ?Print Version ?Bookmark and Share

Keywords:zarlink semiconductor? ldd?

The two new laser diode drivers (LDDs) from Zarlink Semiconductor are touted by the company to deliver industry-leading DVD/CD write/rewrite performance for optical disc drives used in home entertainment and electronics applications.

"Designers of new systems incorporating DVD burner technology require LDDs that tackle the critical issues of speed and supply," said Phil Dorning, engineering manager for Zarlink's Consumer Communications. "With these new devices, Zarlink delivers a powerful combination of high-performance together with end-to-end process reliability and engineering support."

The ZL40539 device is a four-channel device capable of driving separate 650nm DVD and 780nm CD lasers in high-speed "super combo" recorder systems. The LDD includes one 150mA low-noise read channel with 100x current gain, and three 500mA write channels with current gains of 250x, 150x and 100x. Combined write channels can deliver a 700mA pulse to the laser diodesthe industry's most powerful write output, the company added.

With high current output channels, the ZL40539 LDD can write a x16 DVD and x52 CD using a single channel. In comparison, competing devices require designers to combine several output channels to reach the power requirements necessary to write DVDs and CDs at high speeds. Timing inaccuracies caused by combining channels, known as skew, result in slower overall system speeds and corrupted discs.

In addition, Zarlink said, the ZL40539 also delivers the industry's fastest high-current switching times, with guaranteed rise times of 1.2ns and fall times of 1.4ns, and typical performance of 0.9ns rise time and 1.1ns fall time over the full current range. These new LDD's write channels are controlled through an integrated LVDS interface, which provides low-noise, high-speed data transmission over ribbon cables between the controller chip and the optical pickup unit. The LVDS interface also allows the write strategy to be inexpensively and efficiently incorporated into motherboard chips, reducing the overall cost of the optical pickup unit.

Meanwhile, the ZL40518 LDD is a three-channel device with a performance that cost-effectively supports existing x4 and x8 DVD recorder systems, as well as advanced high-speed x52 CD recorder units.

The product features one switched 250mA low-noise read channel with 100x current gain, and two switched 250mA write channels with gains of 250x and 150x. Switching two combined write channels allows over 450mA of total output current to the laser diode. Each channel is controlled through an integrated CMOS logic-compatible control interface to cost-effectively support high-speed CD and existing DVD recorder systems. It delivers typical 0.9ns rise time and 1.1ns fall time rates, and guaranteed rise and fall times of 2ns.

Both the ZL40539 and ZL40518 provide ultra-stable performance at the maximum junction temperature of 150C. Thermal management is a critical design issue, as both the laser diode and its driver generate significant heat within the confined optical pickup unit. The devices also include a high performance, low harmonic switched oscillator with a programmable frequency range of 200MHz to 500MHz and 20mA to 100mA peak-to-peak. By suppressing laser noise when reading optical discs, the oscillator helps deliver superior audio and video playback quality.

The ZL40539 device is available in 6-by-5mm, 32-pin QFN packaging, and is priced at $1.20. The ZL40518 is housed in a 16-pin SSOP package, and is priced at 73 cents. Both prices are for 1,000-unit orders. Evaluation boards are available for both devices.





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