The AT78C1503 is a programmable DVD/CD channel responsible for servo algebra, gain control, equalization, bit detection and clock extraction for CD-ROM, DVD-ROM, DVD-R, DVD-RW and DVD-RAM formats. Programmable features allow data rates up to 5X DVD. Also, for DVDRAM functionality, the channel serves the write path providing laser power control and pit asymmetry detection. Up to 2X DVD write speeds are supported for DVD-R, DVD-RW and DVDRAM. The extracted wobble frequency is supplied to the AT78C1507 companion chip which in turn synthesizes the write clock. The AT78C1507 is the companion chip to the AT78C1503 DVD/CD Read Channel and the AT78C1504 DVD/CD Automatic Laser Power Controller. Working in conjunction with the read channel, the AT78C1507 is responsible for wobble clock synthesis for DVD-R and DVD-RAM formats. In addition, the two parts working together also support pre-pit data and clock recovery for the DVD-R format. Four separate inputs are provided to enable the AT78C1507 to perform tracking servo algebra, using just the outrigger photo detector signals (E, F, G, H for example) coming from the OPU. This extends the range of supported tracking servo algebra functions for the 1503-1507 combination. Lastly, OPC capability is supported for efficient writing of DVD-R, DVD-RAM and CD-R disks. |