X9319 Datasheet, PDF (6/10 Pages) Xicor Inc. – Digitally Controlled Potentiometer (XDCP)

X9319
PIN DESCRIPTIONS
R_H and R_L
The high (R_H) and low (R_L) terminals of the X9319 are
equivalent to the fixed terminals of a mechanical
potentiometer. The terminology of R_L and R_H refer-
ences the relative position of the terminal in relation to
wiper movement direction selected by the U/D input
and not the voltage potential on the terminal.
R_W
R_w is the wiper terminal and is equivalent to the mov-
able terminal of a mechanical potentiometer. The posi-
tion of the wiper within the array is determined by the
control inputs. The wiper terminal series resistance is
typically 40Ω.
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 X9319
will be placed in the low power standby mode until the
device is selected once again.
PIN CONFIGURATION
DIP/SOIC
INC 1
8
V_CC
U/D
2 _X9319 7
CS
R_H
3
6
R_L
V_SS
4
5
R_W
PIN NAMES
Symbol
R_H
R_W
R_L
V_SS
V_CC
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 X9319: 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, R_W.
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,
multiple taps are connected to the wiper for t_IW (INC to
V_W change). The R_TOTAL value for the device can tem-
porarily 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 mem-
ory. When power is restored, the contents of the
memory are recalled and the wiper is set to the value
last stored.
REV 1.7 7/10/03
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