The EL691x family are highly integrated laser diode drivers designed to support multi-standard writable optical drives. They accomplishes this by incorporating a waveform generator wherein the diode currents and timing details can be programmed before operation. The data input circuitry inspects the NRZ serial data waveform and generates programmed waveforms in recognition of 3, 4, 5, or 6 or more clock periods of space changing to 3, 4, 5, or 6 or more clock periods of mark, and vice versa. The parts also have an IV amplifier with concurrent read and write sampling. The gains of the IV amplifier are programmable, eliminating the need for external potentiometers.
The architecture allows reprogramming of the timers to support different media, DVD or CD standards, and different speeds. The programming is accomplished through a serial interface port. Two outputs are provided to support duallaser multi-standard optical heads. The clock and NRZ inputs can be either standard CMOS or LVDS, selectable through a program bit.
The EL691x family operates on a 5V supply for the analog circuits and a 3.3V supply for the digital circuits. |
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Complete programmable laser diode driver
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350mA maximum total output
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8-bit x 8-bit multiplying DAC output provides 8-bit full scale adjustment and 8-bit resolution at any full scale output
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100ps timer resolution
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Two laser outputs allows read/ write DVD and CD combinations
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Programmable waveform values support CD-R, CD-RW, DVD-RAM, DVD-R, DVD-RW, DVD+R, and DVD+RW
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Two analog inputs support slope and read APC
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HFM oscillator programmable to 100mAP-P from 100MHz to 500MHz
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PLL allows reduced-frequency clock on flex cable
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Separate serial input works up to 100MHz
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Dual sampled IV amplifier with programmable sample select and gain select
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Programmable HFM offset when HFM is off
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