UR8HC007-001 Datasheet, PDF (11/18 Pages) Semtech Corporation – Input Device and Power Management Companion IC for Jupiter Devices

ZERO-POWER^TM OPERATION OF PS/2 PORTS
The Juno™ implements the
Semtech-patented "Message loss-
less wake-up™" method to operate
all three PS/2 ports. This method
enables the controller to interface
with devices attached to its PS/2
ports while still operating in the
"Stop" mode. Typical power
consumption of the PS/2 ports is
therefore 1 µA.
If a PS/2 device reports a data
packet, the controller will exit the
"Stop" mode for as long as it takes
to process the device message and
relay the information, if necessary,
to the Host system. This operation
is done transparently to the Host,
without any message loss or any
response delays from the input
devices.
PS/2 PORTS
The UR8HC007-001 provides three PS/2 ports for the hot-plug connection of
an external keyboard, an external mouse and an internal mouse.
All of the internal and external devices are active at all times. Data from
both the external and internal keyboards and mice are merged and
seamlessly presented to the system.
5-Volt Tolerant PS/2 ports
The UR8HC007 controller can be powered by a power supply between 3
and 5 Volts (+/- 10%). Even when the USAR controller is powered by a 3-
Volt supply, the three PS/2 ports can directly interface with 5-Volt powered
devices — without the need of any external level-shifting circuitry. The Host
can enable or disable all the external PS/2 ports simultaneously, in sync with
the 5-Volt power plane that powers them. Alternatively, it can select any
PS/2 port selectively, through the "HID enable/disable control" register.
PS/2 Mouse Handling
The Juno^TM provides a port for the connection of an internal PS/2 mouse.
This port supports MouseWheel functionality.
This unique technology allows
computers to operate at their
minimum power consumption state
even with PS/2 devices attached.
Systems that employ an internal
pointing device, such as a touch
pad or a force stick, can benefit the
most from this feature, since the
pointing device will force the
controller to exit its "Stop" mode only
when there is data to be reported.
An internal mouse connected to a system’s PS/2 port consumes a significant
amount of power as it must always be “on.” A mouse connected to one of
Juno’s™ PS/2 ports consumes minimal power because the Juno™ will
power down even when the internal mouse is connected and active.
Copyright ©1998-2001 Semtech Corporation
11
DOC8-007-001-DS-108
www.semtech.com