X9319_14 Datasheet, PDF (5/8 Pages) Intersil Corporation – Digitally Controlled Potentiometer

A.C. Timing
X9319
CS
t_CI
INC
U/D
t_IW
R_W
t_CYC
t_IL
t_IH
t_ID
t_IC
t_DI
MI ⁽³⁾
t_CPHS
90% 90%
10%
t_CPHNS
t_F
t_R
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 references 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 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 40Ω.
Up/Down (U/D)
The U/D input controls the direction of the wiper movement
and whether the counter is incremented or decremented.
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.
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 temporarily be reduced by a
significant amount if the wiper is moved several positions.
When the device is powered down, the last wiper position
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.
Instructions and Programming
The INC, U/D and CS inputs control the movement of the wiper
along the resistor array. With CS set LOW, the device is
selected and enabled to respond to the U/D and INC inputs.
HIGH-to-LOW transitions on INC will increment or decrement
(depending on the state of the U/D input) the seven bit counter.
The output of this counter is decoded to select one of one
hundred wiper positions along the resistive array.
The value of the counter is stored in nonvolatile memory
whenever CS transitions HIGH while the INC input is also
HIGH.
The system may select the X9319, move the wiper and
deselect the device without having to store the latest wiper
position in nonvolatile memory. After the wiper movement is
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FN8185.3
July 31, 2014