UR6HCPS2-SP40 Datasheet, PDF (15/22 Pages) Semtech Corporation – Converts PS/2 Data to Serial or SPI

POWER MANAGEMENT
Modes of Operation
The UR6HCPS2-SP40 has two
modes of operation relating to its
power consumption.
The "Stop" mode is the lowest
power consumption mode. In this
mode, the oscillator is stopped and
the IC consumes only 1 µA of
leakage current. This is the default
mode to which the IC will revert to
when it is idle.
The "Run" mode is entered briefly,
only to process an event or while an
interrupt-generating signal condition
persists. The IC will remain in this
mode until there are no tasks to
handle, such as PS/2 reports or
inititalization of PS/2 devices.
The PS/2 devices connected to the
four external PS/2 ports are
initialized at different sampling
rates, depending on the port: PS/2
port 0 and PS/2 port 1 to 100
packages per second and 40
packages per second for PS/2 port
3 and PS/2 port 4. When mice
plugged into PS/2 port 0 and 1 are
moved, the PS2Adapt^TM will typically
stay in stop mode for 25% of the
working time. When mice plugged
into PS/2 port 3 and 4 are moved
with a slower sampling rate, the
PS2Adapt^TM will typically stay in stop
mode for 72% of working time.
Therefore, we recommend that PS/2
port 3 and 4 are used for mice, if
there is no specific requirement of
mice sampling rate.
Note 1: When there is no mouse motion, all
ports have same power consumption, less
than 1µA.
Note 2: When a keyboard is plugged into
these ports, the rate of the power saving are
same, less than 1µA.
The PS2Adapt^TM implements two power management methods: system-
coordinated power management and Self Power Management^TM (SPM).
System-coordinated power management is implemented by the _PWR_OFF
pin (Power Off). If the _PWR_OFF pin is low, the PS2Adapt™ will disable all
external PS/2 device reports to save power and to turn off keyboard Leds.
Self-Power Management^TM is a method implemented by the PS2Adapt^TM IC
that, independently of any system intervention, results in the lowest power
consumption possible within the given parameters of its operation. Through
Self Power Management^TM, the PS2Adapt^TM IC is capable of typically
operating at only 1 µA, independent of the state of the system. Self Power
Management^TM primarily determines the actual power consumption of the
IC.
Even when the Host is in the active state, the IC can still operate most of
the time at only 1 µA, even with active external PS/2 devices attached to it.
PWR_OFF Pin Low
OR
No Task
Stop
Run
PWR_OFF Pin High
AND
External PS/2 Report
Copyright Semtech, 2002-2001
15
DOC6-PS2-SP40-DS-102
www.semtech.com