UR5HCFJL Datasheet, PDF (7/20 Pages) Semtech Corporation – Zero-PowerTM Keyboard Encoder for Portable Systems

STATES OF OPERATION
The GreenCoder^TM has three states
of operation, implemented to
minimize the power consumption of
the keyboard subsystem. The
following diagram illustrates the
three states of operation of the
GreenCoder^TM.
SLEEP
STATE
STAND BY
STATE
USING THE GREENCODER^TM FOR SYSTEM MANAGEMENT TASKS
The GreenCoder^TM provides an ideal complement to low-power chip sets
targeted to the portable and mobile computing market. The GreenCoder^TM
can be used to handle several system management tasks for small, portable
system designs, thus saving space and additional components for the
System Designer. Such system management tasks include those listed
below.
However, since most of the system management tasks are application and
hardware-dependent, detailed implementation information is outside the
scope of this document. For application examples and sample schematics,
contact Semtech Technical Support.
ACTIVE
STATE
Figure 2: States of Operation of
UR5HCFJL
Most of the time, the GreenCoder^TM
is in the Sleep State. Power
consumption in this state is
approximately 2 µA at 5 Volts of
operation. The GreenCoder^TM enters
the Active State only when there is
an event to process, such as a
keystroke, a command from the
system, or data from the external
PS/2-compatible device.
System shut-down/wake-up signal
The GreenCoder^TM can provide the system power management unit with a
shut-down/wake-up signal which can be invoked either by a special
keyboard combination or after a programmed period of user inactivity.
Note: Self-Power Management^TM is a feature protected under Semtech Corp. patent and copyright rights.
Purchase of any version of the UR5HCFJL encoder conveys a license to utilize the Self-Power Management
feature only through use of the UR5HCFJL in a PS/2-compatible keyboard subsystem.
The GreenCoder^TM enters and stays
in the Stand-By State if an external
device is connected to the auxiliary
port or if one or more LEDs are
turned on.
In the Stand-By State, the IC
consumes approximately 600 µA at
5 Volts. Transition from one state to
the other does not require any input
from the system.
Copyright Semtech, 1997-2001
7
DOC5-FJL-DS-106
www.semtech.com