IC LASER DRIVER 4CHAN 5.5V 28LLP

LMH6525SPX/NOPB

Manufacturer Part NumberLMH6525SPX/NOPB
DescriptionIC LASER DRIVER 4CHAN 5.5V 28LLP
ManufacturerNational Semiconductor
SeriesLMH™
TypeLaser Diode Driver (CD/DVD)
LMH6525SPX/NOPB datasheet
 

Specifications of LMH6525SPX/NOPB

Number Of Channels4Voltage - Supply4.5 V ~ 5.5 V
Current - Supply33mAOperating Temperature-40°C ~ 85°C
Package / Case28-LLPMounting TypeSurface Mount
Lead Free Status / RoHS StatusLead free / RoHS CompliantOther namesLMH6525SPX
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LMH6525/LMH6526
Four–Channel Laser Diode Driver with Dual Output
General Description
The LMH
6525/6526 is a laser diode driver for use in
combination 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. Func-
tionality includes read, write and erase through four separate
switched current channels. The channel currents are
summed together at the selected output to generate multi-
level waveforms for reading, writing and erasing of optical
discs. The LVDS interface delivers DVD write speeds of 16x
and higher while minimizing noise and crosstalk. The
LMH6525/6526 is optimized for both speed and power con-
sumption 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 600 mA or greater. The chan-
nel currents are set through four independent current inputs.
An on-board High-Frequency Modulator (HFM) oscillator
helps reduce low-frequency noise of the laser and is enabled
by applying LVDS levels on the ENOSC pins for the
LMH6525, while the LMH6526 is enabled by applying an
asymmetrical signal on the ENOSC pin. The fully differential
oscillator circuit minimizes supply line noise, easing FCC
approval of the overall system. The SELA/B pin (active
HIGH) selects the output channel and oscillator settings.
External resistors determine oscillator frequency and ampli-
tude for each setting. The write and erase channels can be
switched on and off through dedicated LVDS interface pins.
Block Diagrams
LLP
®
is a registered trademark of National Semiconductor.
LMH
is a trademark of National Semiconductor Corporation.
© 2005 National Semiconductor Corporation
Features
n Fast switching: Rise and fall times: 0.6/1.0 ns.
n Low Voltage Differential Signaling (LVDS) channels
enable interface for the fast switching lines
n Low output current noise: 0.24 nA/
n Dual Output: Selectable by SELA/B pin (active HIGH)
SELA = LMH6526
n 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
600 mA minimum combined output current
n 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
n Complete shutdown by ENABLE pin
n 5V single-supply operation
n Logic inputs TTL and CMOS compatible
n Space saving Leadless Leadframe Package (LLP
n LMH6525 has differential enable oscillator inputs
n LMH6526 has single ended enable oscillator inputs
Applications
n Combination DVD/CD recordable and rewritable drives
n DVD camcorders
n DVD recorders
20110108
DS201101
June 2005
SELB = LMH6525
®
-28)
20110109
www.national.com

LMH6525SPX/NOPB Summary of contents

  • Page 1

    ... External resistors determine oscillator frequency and ampli- tude for each setting. The write and erase channels can be switched on and off through dedicated LVDS interface pins. Block Diagrams LLP ® registered trademark of National Semiconductor. LMH ™ trademark of National Semiconductor Corporation. © 2005 National Semiconductor Corporation Features n Fast switching: Rise and fall times: 0 ...

  • Page 2

    ... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. ESD Tolerance Human Body Model (Note 2) Machine Model (Note 3) + − Supply Voltages V – V Differential Input Voltage Output Short Circuit to Ground (Note 4) ...

  • Page 3

    DC Electrical Characteristics Unless otherwise specified, all limits guaranteed for T Symbol Parameter V TTL High Voltage THI V TTL High Voltage THI V Enable High Voltage EHI I Supply Current, Power Down Spd I Supply Current, Read Mode, ...

  • Page 4

    AC ELECTRICAL CHARACTERISTICS Unless otherwise specified, all limits guaranteed for T apply at the temperature extremes. Symbol Parameter T Disable Time Oscillator DO T Enable Time Oscillator EO T Disable Time Oscillator DO T Enable Time Oscillator EO Note ...

  • Page 5

    Connection Diagrams 28-Pin LLP (LMH6525) Top View Pin Description Pin # Description 1. Laser driver output channel A 2. LVDS Oscillator Enable pin 3. LVDS Oscillator Enable pin B (only LMH6525) 4. Read Channel Enable pin 5. Chip Enable pin ...

  • Page 6

    Pin Description (Continued) Pin # Description 27. Laser driver output channel B 28. Ground Connection B Truth Tables IOUT Control ENABLE ENR Oscillator Control ENABLE ENOSC 0 X ...

  • Page 7

    Waveforms (Continued) Enable Timing Read Timing Write Timing Oscillator Timing 7 20110111 20110112 20110113 20110114 www.national.com ...

  • Page 8

    Detailed Block Diagram www.national.com 20110115 8 ...

  • Page 9

    Application Schematic 9 20110116 www.national.com ...

  • Page 10

    Typical Performance Characteristics Oscillator Amplitude vs. R Oscillator Frequency vs. R Noise vs. Frequency www.national.com + ± 25˚ 5V Oscillator Amplitude vs 20110103 F 20110104 Headroom & Output Current vs. Total Input ...

  • Page 11

    Application Section CIRCUIT DESCRIPTION General & Spec The LMH6525/6526 is a 4-channel-input, dual-output laser driver. The dual outputs are meant to drive two different laser diodes, one for CD reading and writing and one for DVD reading and writing. The ...

  • Page 12

    Application Section (Continued) voltage of the part at the power pin is 5.25V and this means the supply line loss is 0.25V 5.5V supply voltage the part can drive laser diodes with a forward voltage in access of ...

  • Page 13

    ... A helpful tool for calculating impedances of transmission lines is the: ‘Transmission Line Rapidesigner’ available from the National Semiconductor Interface Products Group. Application Note AN-905 details the use of this handy software tool. ...

  • Page 14

    Application Hints (Continued) FIGURE 4. Decoupling Capacitors OSCILLATOR RESISTORS The resistors and/or potentiometers used to set oscillator frequency or amplitude should be as close to the part as possible. If the grounds are split when using a single-sided flex circuit, ...

  • Page 15

    ... BANNED SUBSTANCE COMPLIANCE National Semiconductor manufactures products and uses packing materials that meet the provisions of the Customer Products Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2. ...