UR7HCTS2-P840-FG Semtech Corporation, UR7HCTS2-P840-FG Datasheet - Page 5

• Manufacturer Part Number: UR7HCTS2-P840-FG
• Description: High-Performance/ Low Power PS/2 Touch Screen Controller/Digitizer
• Manufacturer: Semtech Corporation

The "Stop" mode is the lowest
power consumption mode. In this
mode, the oscillator is stopped and
the IC consumes only the leakage
current. This is the default mode to
which the IC will revert when it is
idle. An event or signal conditions
wake-up the IC. The
ScreenCoder
operate most of the time at only
1uA, even when the host is in the
active state, and with active
external PS/2 device attached to
the ScreenCoder
external PS/2 device sends a data
packet, the ScreenCoder
exit the "Stop" mode for as long as
it takes to process the message
and relay the information to the
system. This operation is done
transparently to the host, without
any data loss or any response
delay from the input device.
System-coordinated Power
Management
Normal Operation State
In normal operation state, both
_PWR_DOWN and XPWRS pins are
in high state. ScreenCoder
operations are controlled by Self-
Power Management
Critical Suspend
At any time, the Host may negate
the _PWR_DOWN pin in order to
force the ScreenCoder
"Critical suspend" mode. This
signal can be activated (driven
low) due to specific conditions of
the Host's operations (for example,
a discharged battery), or due to
actions of the Operating System or
BIOS.
Copyright ©1999-2001 Semtech Corporation
DOC7-TS2-P840-DS-106
POWER MANAGEMENT (CON’T)
TM
PS2 can still
TM
PS2. If an
TM
.
TM
PS2 into a
TM
TM
PS2 will
PS2
During the "Critical suspend", the ScreenCoder
pointing activities. However, the communications with the Host are still
enabled.
External PS/2 power down
The ScreenCoder
pointing device through the XPWRS pin. If the IC senses that the external
PS/2 device has been powered-down by the host, it will actively eliminate
shot-through current in the input buffers for the clock and data lines by
driving both low.
The ScreenCoder
pointing device when the power to the external PS/2 port is restored.
Figure 2: Semtech’s System-coordinated Power Management
5
Figure 1: Semtech’s Self-Power Management
POWER MANAGEMENT (CON’T)
power down
RUN
Ext Mouse
TM
TM
_PWR_DOWN=0
PS2 monitors the power state of the external PS/2
UR7HCTS2-P840 will re-initialize the external PS/2
_PWR_DOWN=1
Mouse hot plug or Data Packet,
and XPWRS=0
System Request To Send,
Touch Screen activity,
Button press
_PWR_DOWN=1
_PWR_DOWN=1
1s of inactivity
and XPWRS=0
and XPWRS=1
Critical Suspend
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_PWR_DOWN=1
and XPWRS=1
TM
TM
will shut down all of the
State
_PWR_DOWN=0
Normal State
STOP