UR5HCSPI View Datasheet(PDF) - Semtech Corporation
Part Name
Description
MFG CO.
'UR5HCSPI' PDF : 20 Pages View PDF
PIN DESCRIPTIONS
VCC and VSS
VCC and VSS are the power
supply and ground pins. The
UR5HCSPI will operate from a 3-5
Volt power supply. To prevent noise
problems, provide bypass
capacitors and place them as
close as possible to the IC with the
power supply. VX, where available,
should be tied to Vcc.
OSCI and OSCO
OSCI and OSCO provide the input
and output connections for the on-
chip oscillator. The oscillator can
be driven by any of the following
circuits:
- Crystal
- Ceramic Resonator
- External Clock Signal
The frequency of the on-chip
oscillator is 2 MHz.
_RESET
A logic zero on the _RESET pin will
force the UR5HCSPI into a known
start-up state. The reset signal can
be supplied by any of the following
circuits:
- RC
- Voltage monitor
- Master system reset
MOSI, MISO, SCK, _SS, _ATN
These five signals implement the
SPI interface. The device acts as a
slave on the SPI bus. The _SS
(Slave Select) pin should be tied to
ground if not used by the SPI
master. The _ATN pin is asserted
low each time the UR5HCSPI has a
packet ready for delivery. For a
more detailed description, refer to
the SPI Communication Channel
section on page 9.
_IOTEST and _WKU
“Input Output Test” and “Wake Up”
pins control the stop mode exit of
the device. The designer can
connect any number of active low
signals to these two pins through a
17K resistor, in order to force the
device to exit the stop mode. A
sample circuit is shown on page 15
of this document.
All the signals are “wire-anded.”
When any one of these signals is
not active, it should be floating (i.e.,
these signals should be driven from
“open-collector” or “open-drain”
outputs). Other configurations are
possible; contact Semtech.
R0-R 7
The R0-R7 pins are connected to
the rows of the scanned matrix.
Each pin provides an internal pull-
up resistor, eliminating the need for
external components.
C0-C9
C0 to C9 are bi-directional pins
connected to the columns of the
scanned matrix. When a column is
selected, the pin outputs an active
low signal. When the column is de-
selected, the pin turns into high-
impedance.
C10/WUKO
The C10/WUKO pin acts
alternatively as column scan output
and as an input. As an input, the
pin detects the “Wake-Up Keys
Only” signal, typically provided by
the host CPU to indicate that the
user has turned the unit off. When
the device detects an active high
state on this pin, it feeds this
information into the “Keyboard State
Control” unit, in order to disable the
keyboard and enable the
programmed wake-up keys.
C11/_LID
The C11/_LID pin acts in a similar
manner to the C10/WUKO. This pin
is typically connected to the LID
latch through a 150K resistor, in
order to detect physical closing of
the device cover. When the pin
detects an active low state in this
input, it feeds this information into
the “Keyboard State Control” unit, in
order to disable keys inside the
case and enable only switches
located physically on the outer
body of the H/PC unit.
LED0, LED1 and LED2
These three pins provide an active
low drive for LED indicators. The
programming of these pins is
explained in the LEDs section on
page 8 of this document.
Copyright Semtech 1997-2001
4
DOC5-SPI-DS-117
www.semtech.com
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