LMH6525

The LMH6525/6526 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. 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 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 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.