W99681CF

·  Fully compliant with USB Specification Revision 1.1
·  Supports for full speed devices with maximum 12 Mb/s USB bandwidth
·  Uses no more than 8 Mb/s USB bandwidth to prevent saturation of the USB bus
·  Provides multiple alternate settings for various isochronous bandwidth consumptions
·  Does not use isochronous bandwidth for default alternate setting 0
·  Complies with USB power management requirements
·  USB Control and Isochronous transfers
·  On-chip USB full speed transceivers
·  Bus-powered high power devices
·  Fully compliant with ISO/IEC 10918-1 international JPEG standard
·  On-chip DCT, quantization, zig-zag scan, and Huffman encoder
·  Contains two AC and two DC Huffman code tables, and two programmable quantization tables
·  Supports baseline sequential mode in YCbCr4:2:2 or YCbCr4:2:0 non-interleaved scan
·  Encodes in sub-QCIF (128x96), QCIF (176x144), CIF (352x288), SIF (352x240), 320x240, or VGA (640x480) picture format
·  Encodes sub-QCIF/QCIF/CIF/SIF/320x240 format at 30 frames per second (fps), VGA format at 10~15 fps
·  Direct connect to digital camera through an 8- or 16-bit data bus
·  Glueless interface to NTSC/PAL TV decoder
·  Input video format compliant with YCbCr 4:2:2 CCIR 601 standard
·  Built-in cropping, arbitrary scaling, and filtering functions for digital pan and zoom camera control

The W99681CF is a digital video processing chip offered by Winbond to facilitate adapterless connection between digital video camera and personal computer for video and still image capturing and editing, video e-mail, and video conferencing applications. Low-cost, high-performance, and high-
quality digital video camera can be realized by using Winbond¢s W99681CF, which includes UniversalSerial Bus (USB) technology and the international standard JPEG compression.

The digital video camera is becoming the next great input device for the PC. USB is now a common PCstandard for connecting peripheral products, which features low cost, hot-attachable plug and play,adequate 12 Mb/s full speed bandwidth, and simultaneous attachment of multiple devices. The W99681CF has built-in full speed USB controller which benefits from using the isochronous data transfer mode of the USB bus, and which is compliant with the full power management requirements of the USB specification, including startup, operating, and suspend modes. To prevent saturation of the USB bus, the W99681CF uses no more than 8 Mb/s of available bandwidth to ensure the continued operation of other low bandwidth devices such as USB mice and keyboards.

Although USB provides a low-cost solution for low to medium speed peripherals, its 12 Mb/s bandwidth is not enough for high-quality and high-performance digital video camera. High-quality and low-cost compression is necessary to boost frame rate for a high-performance digital video camera. The W99681CF has built-in the baseline JPEG compression, which corresponds to the ISO/IEC international standard 10918-1, with YCbCr4:2:2 or YCbCr4:2:0 components in non-interleaved scan.The baseline JPEG implementation in the W99681CF includes Discrete Cosine Transform (DCT),quantization, zig-zag scan, and Huffman encoder. With JPEG compression, the W99681CF can easilyachieve good quality 30 frames per second (fps) in CIF resolution (352¥288) and 10~15 fps in VGA resolution (640¥480) by consuming no more than 8 Mb/s USB bandwidth.

The W99681CF can accept NTSC, PAL, or VGA video in 8- or 16-bit YCbCr4:2:2 format, square or rectangular pixels, and converts to sub-QCIF (128¥96), QCIF (176¥144), CIF (128¥96), SIF (352¥240),320¥240, or VGA (640¥480) format. Built-in cropping window control and arbitrary scaling in both the horizontal and vertical directions can serve as the digital pan and zoom over a user-specified region for camera control.

In addition to USB interface,the W99681CF also supports an 8-bit microcontroller interface for portable PC camera applications. Up to 24 still images in 640¥480 VGA format can be captured, JPEG compressed, and stored into an external 2 Mbytes Flash memory when in the portable mode.

An on-chip DRAM W99681CF controller is used to interface to SDRAM or EDO DRAM through a 16-bit data bus.An external serial E2 PROM is also supported if IHV-specific Vendor ID and Product ID are needed. The IHV-specific information can be also provided by an external microcontroller if present to save the cost of an E2 PROM. The W99681CF is a 3.3 V device with TTL-compatible 3.3 V or 5.0 V I/O, and is packaged in a 128L QFP.