GENERAL DESCRIPTION
W81281 is a low cost, high integration single-chip microcontroller with Universal Serial Bus (USB) interface for keyboard application, it includes the core of Winbond 8-bit microprocessor W78C52 which works on 6MHz. It implements a standard PC keyboard and enables connection to host system through low-speed (1.5Mhz) USB connection . It complies with USB Specification Revision 1.0 and HID Class Definition Revision 1.0.
For Keyboard application, W81281 supports an 18 X 8 keyboard scan matrix, which allows suspend wake up, and also provides a port for PS/2 mouse. It consists of an 8051 compatible CPU core, a 6K-byte ROM, a 256-byte SRAM, and three 16-bit programmable timers.
W81281 supports one device address and five endpoints, one bi-directional endpoint for Control transfer and four unidirectional endpoints for Interrupt IN transfer. Through modification of firmware of W78C52, it can be used for multifunction device design, such as USB-IR receiver and any Slow-Speed (1.5Mhz) USB peripheral device controller.

FEATURES
• Fully compliant with USB spec. Rev.1.0 and HID Class Rev. 1.0
• Supporting one device address and five endpoints (one Control transfer, four Interrupt transfer)
• Implementing USB keyboard with PS/2 mouse connection
• Microsoft Intellimouse(3D mouse) Supported
• Supporting 8-bit sense (row) input with wake up interrupt on falling edge, internal pull-ups
• Supporting 18-bit drive (column) output, open drain with pull-ups
• 8-bit 8051 compatible CPU core
• 6K-byte ROM
• 256-byte SRAM
• 3 direct drive LED outputs with internal series resisters
• Supporting warm reset
• Built-in low voltage reset and EFT/ESD protection circuit
• Built-in Watch-Dog Timer for device recovery
• Support Win98 system control function
• Support suspend/wake-up function, suspend current under 500µA
• Internal 3.3V regulator supported
• 40-pin DIP, 28-pin SOP and 48-pin LQFP packages
• 5V CMOS Device