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03/06/00

GL651USB USB KEYBOARD HUB CONTROLLER

Version 1.0

2

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 general-

purpose 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.

For giving more design flexibility, the power supply of GL651USB can be switched

automatically: self-power or bus-power. In the same way, vendors can pullup/pulldown

the SELF pin to support only self/bus power if they have cost issue. The GL651USB can

be configured as ganged/individual mode for hub functions by strapping through

pullup/pulldown the SUSPND pin. To prevent from abnormal current consumption of

downstream port devices, the GL651USB supplies power enable flags by reading the

over-current flags. By hub LED, The GL651USB also supports smart traffic indication,

i.e., the higher data traffic flows through one port, the higher frequency of that port’s

LED blinks. In order to minimize the power consumption, the GL651USB will turn LED

off and stop the clock automatically when it is suspended.

The GL651USB is the most featured and flexible product for those venders who are

looking for “USB Keyboard with Hub” solution. Besides, vendors can easily modify their

board circuits to meet their own requirement if they have product differentiation or cost

issues. Further more, if vendor has the requirement of saving their package cost, COB

component also can be supplied by request.