FUNCTION OVERVIEW
The GL651USB is an USB keyboard hub with 1 upstream port and 2 downstream ports. It integrates USB keyboard and hub in a single chip to add extra value to traditional keyboard and lower its total cost. The GL651USB uses an 8-bit RISC-like uC to encode/decode the host commands and to decode the keyboard matrix data. Its 8 generalpurpose I/O(GPIO) pins and the uC-based structure make the implementation of customization very easy. The GL651USB supports 20 drive pins to meet the diversity of keyboard matrix. Besides, 5 GPIO pins support the LED driving, 3 for keyboard and 2 for hub. Hence vendors can decide whether or not to enable the hub LED function easily.

FEATURES
● High performance and low-cost solution for USB keyboard with hub solution
● USB Specification Compliance
   - Conforms to USB specification Rev. 1.1
   - Conforms to HID Class specification Rev. 1.0
   - Supports 1 device address for hub, 1 device address for keyboard
   - Supports 2 endpoints of hub, 3 endpoints for keyboard
● 8-bit micro-processor
   - RISC-like architecture
   - USB optimized instruction set
   - Single cycle instruction execution
   - Operation Speed: DC to 24 MHz clock input
   - Performance: 12 MIPS @ 24MHz
● I/O ports
   - Up to 20 output pins for key matrix drive pin
   - Up to 8 input pins for key matrix sense pin
   - Up to 5 I/O pins with LED drive capability : 3 for keyboard, 2 for hub
   - Up to 8 general purpose I/O pins for customization
● Internal memory
   - 80 bytes of RAM
   - 3.25K ´ 14 of program ROM
   - larger size of ROM makes it possible for customization
● On-chip 3.3v output
   - No external regulator required
● Integrated USB transceiver
● 12 MHz external clock
● Improved output drivers with slew-rate control to reduce EMI
● Internal power-on reset(POR)
● Internal power-fail detector for ESD recovery
● Support suspend/normal mode power management
● Remote wakeup is supported for both keyboard and hub
● Support power management for downstream port devices
● Automatic switching between self/bus powered mode
● Smart LED traffic indicator
   - The higher data traffic flows through the hub downstream port, the higher frequency that port’s LED will blink.
● 100 pin LQFP package for demo, COB structure is supported