LMH6533

Four –Channel Laser Diode Driver with Dual Output,

LVDS Interface and HFM Oscillator

General Description

tion DVD/CD recordable and rewritable systems. The part

contains two high-current outputs for reading and writing the

DVD (650 nm) and CD (780 nm) lasers. Functionality in-

cludes read, write and erase through four separate switched

current channels. The channel currents are summed to-

gether at the selected output to generate multilevel wave-

forms for reading, writing and erasing of optical discs. The

LVDS interface delivers DVD write speeds of 12x and higher

while minimizing noise and crosstalk. The LMH6533 is opti-

mized for both speed and power consumption to meet the

demands of next generation systems. The part features a

150 mA read channel plus one 300 mA and two 150 mA write

channels, which can be summed to allow a total output

current of 500 mA or greater. The channel currents are set

through four independent current inputs.

The part is manufactured in National Semiconductor’s

and trench isolation for very high switching speeds at low

power levels. An on-board High-Frequency Modulator (HFM)

oscillator helps reduce low-frequency noise of the laser and

is enabled with the ENOSC pin. The fully differential oscilla-

tor circuit minimizes supply line noise, easing FCC approval

of the overall system. The SELB pin (active HIGH) selects

the output channel and oscillator settings. External resistors

determine oscillator frequency and amplitude for each set-

ting. The write and erase channels can be switched on and

off through dedicated LVDS interface pins.

Features

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Low voltage differential signaling (LVDS) channels

enable interface for the fast switching lines

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Dual output: Selectable by SELB pin (active HIGH)

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Four independent current channels

— Gain of 300, 300 mA write channel

— Gain of 150, 150 mA low-noise read channel

— Two gain of 150, 150 mA write channels

— 500 mA minimum combined output current

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Integrated AC Coupled HFM Oscillator

— Selectable frequency and amplitude setting by

external resistors

— 200 MHz to 600 MHz frequency range

— Amplitude to 100 mA peak-to-peak modulation

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Complete shutdown by ENABLE pin

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5V single-supply operation

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Logic inputs TTL and CMOS compatible

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Applications

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Combination DVD/CD recordable and rewritable drives

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DVD camcorders

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DVD video recorders

Block Diagram

20027701

May 2004

© 2004 National Semiconductor Corporation

DS200277

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