UR5HCSPI View Datasheet(PDF) - Semtech Corporation
Part Name
Description
MFG CO.
'UR5HCSPI' PDF : 20 Pages View PDF
DATA/COMMAND BUFFER
The UR5HCSPI implements a data
buffer that contains the key
code/command bytes waiting to be
transmitted to the host. If the data
buffer is full, the whole buffer will be
cleared and an "Initialize" command
will be sent to the host. At the
same time, the keyboard will be
disabled until the "Initialize" or
"Initialize Complete" command from
the host is received.
POWER MANAGEMENT UNIT
The UR5HCSPI supports two modes of operation. The following table lists
the typical and maximum supply current (no DC loads) for each mode at
3.3 Volts (+/- 10%).
Current
RUN
STOP
Typical
1.5 1
2.0
Max
3.0
20
Unit
mA
µA
Description
Entered only while data/commands
are in process and if the LEDs
are blinking
Entered after 125 mS of inactivity if
LEDs islow
Power consumption of the keyboard sub-system will be determined
primarily by the use of the LEDs. While the UR5HCSPI is in the STOP
mode, an active low Wake-Up Output from the Master must be connected
to the edge-sensitive _WKU pin of the UR5HCSPI. This signal will be used
to wake up the UR5HCSPI in order to receive data from the Master host.
The Master host will have to wait a minimum of 5 mS prior to providing
clocks to the UR5HCSPI. The UR5HCSPI will enter the STOP mode after a
125 mS period of keypad and/or host communications inactivity, or anytime
the PWR_OK line is asserted low by the host. Note that while one or more
keys are held pressed, the UR5HCSPI will not enter the STOP mode until
every key is released.
Figure 7: The power states of the UR5HCSPI
Stop
- Keyboard
- Switch
- Input transaction
- System wake-up
After Reset
or 125 mS of
inactivity
- After 125 mS of
inactivity and LEDs
are off
Run
While processing
current task
and/or LED(s)
are active
Copyright Semtech 1997-2001
10
DOC5-SPI-DS-117
www.semtech.com
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