X9318 Просмотр технического описания (PDF) - Renesas Electronics
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X9318 Datasheet PDF : 10 Pages
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X9318
PIN DESCRIPTIONS
RH and RL
The high (RH) and low (RL) terminals of the X9318 are
equivalent to the fixed terminals of a mechanical potenti-
ometer. The terminology of RL and RH references the
relative position of the terminal in relation to wiper move-
ment direction selected by the U/D input and not the volt-
age potential on the terminal.
RW
Rw is the wiper terminal and is equivalent to the movable
terminal of a mechanical potentiometer. The position of
the wiper within the array is determined by the control
inputs. The wiper terminal series resistance is typically
40.
Up/Down (U/D)
The U/D input controls the direction of the wiper move-
ment and whether the counter is incremented or decre-
mented.
Increment (INC)
The INC input is negative-edge triggered. Toggling INC
will move the wiper and either increment or decrement
the counter in the direction indicated by the logic level on
the U/D input.
Chip Select (CS)
The device is selected when the CS input is LOW. The
current counter value is stored in nonvolatile memory
when CS is returned HIGH while the INC input is also
HIGH. After the store operation is complete the X9318
will be placed in the low power standby mode until the
device is selected once again.
PIN CONFIGURATION
INC
U/D
RH
VSS
DIP/SOIC
1
8
2 X9318 7
3
6
4
5
VCC
CS
RL
RW
PIN NAMES
Symbol
RH
RW
RL
VSS
VCC
U/D
INC
CS
Description
High terminal
Wiper terminal
Low terminal
Ground
Supply voltage
Up/Down control input
Increment control input
Chip select control input
PRINCIPLES OF OPERATION
There are three sections of the X9318: the control
section, the nonvolatile memory, and the resistor array.
The control section operates just like an up/down
counter. The output of this counter is decoded to turn on
a single electronic switch connecting a point on the
resistor array to the wiper output. The contents of the
counter can be stored in nonvolatile memory and
retained for future use. The resistor array is comprised
of 99 individual resistors connected in series. Electronic
switches at either end of the array and between each
resistor provide an electrical connection to the wiper pin,
RW.
The wiper acts like its mechanical equivalent and does
not move beyond the first or last position. That is, the
counter does not wrap around when clocked to either
extreme.
The electronic switches on the device operate in a
“make before break” mode when the wiper changes tap
positions. If the wiper is moved several positions, multi-
ple taps are connected to the wiper for tIW (INC to VW
change). The RTOTAL value for the device can tempo-
rarily be reduced by a significant amount if the wiper is
moved several positions.
When the device is powered-down, the last wiper posi-
tion stored will be maintained in the nonvolatile memory.
When power is restored, the contents of the memory are
recalled and the wiper is set to the value last stored.
FN8184 Rev 1.00
September 14, 2005
Page 6 of 10
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