General Description
HT82M91A is a 3D mouse encoder chip especially designed for USB applications. The HT82M91A can support the USB Standard Request as well as HID Class Request version 1.0. It can be briefly described as a Holtek 8-bit C with an on-chip USB interface logic. It can use minimal external components to implement three key-switches and four photo-coupler mouse. The USB is specified by the Universal Serial Bus Specification.

Features
• Complete Universal Serial Bus specification compatibility
• Serial Bus Interface Engine (SIE)
• USB transceiver
• Supports three buttons (R, M, L) and three axes (X, Y, Z) input
• Z axis can support two kinds of scroller input (optomechanical and mechanical)
• Single chip solution especially for USB mouse function
• Halt function and wake-up feature reduce power consumption
• Has plug and Play functions
• Minimal external components
• 6MHz crystal oscillator for system clock
• 18-pin DIP package