LMH6525 Datasheet | National Semiconductor

.. June 2005 LMH6525/LMH6526 Four- Channel Laser Diode Driver with Dual Output LMH6525/LMH6526 Four- Channel Laser Diode Driver with Dual Output General Description The LMH™6525/6526 is a laser diode driver for use in bination 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 includes read, write and erase through four separate switched current channels. The channel currents are summed together at the selected output to generate multilevel 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 consumption to meet the demands of next generation systems. The part Features a 150 m A read channel plus one 300 m A and two 150 m A write channels, which can be summed to allow a total output current of 600 m A or greater. The channel 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 amplitude for each setting. The write and erase channels can be switched on and off through dedicated LVDS interface pins. 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 n A/ n Dual Output: Selectable by SELA/B pin (active HIGH) SELA = LMH6526 SELB = LMH6525 n...