X93255_08 Datasheet, PDF (6/7 Pages) Intersil Corporation – Dual Digitally Controlled Potentiometers(XDCPs™)

X93255
Instructions and Programming
The INC, U/D and CS inputs control the movement of the
pertaining wiper along the resistor array. With CS set LOW,
the pertaining potentiometer 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) a 5-bit counter. The output of this counter is
decoded to select one of thirty two wiper positions along the
resistive array.
The value of the counter is stored in nonvolatile memory
whenever each CS transitions HIGH while the pertaining
INC input is also HIGH. In order to avoid an accidental store
during power-up, each CS must go HIGH with V_CC during
initial power-up. When left open, each CS pin is internally
pulled up to V_CC by an internal 30k resistor.
The system may select the X93255, move any wiper and
deselect the device without having to store the latest wiper
position in nonvolatile memory. After the wiper movement is
performed as previously described and once the new
position is reached, the system must keep INC LOW while
taking CS HIGH. The new wiper position will be maintained
until changed by the system or until a power-up/down cycle
recalled the previously stored data. In order to recall the
stored position of the wiper on power-up, the CS pin must be
held HIGH.
This procedure allows the system to always power-up to a
preset value stored in nonvolatile memory; then during
system operation minor adjustments could be made. The
adjustments might be based on user preference, system
parameter changes due to temperature drift, or other system
trim requirements.
The state of U/D may be changed while CS remains LOW.
This allows the host system to enable the device and then
move each wiper up and down until the proper trim is
attained.
Mode Selection
CS INC U/D
MODE
L
H Wiper Up
L
L Wiper Down
H
X Store Wiper Position
H
X
X Standby Current
L
X No Store, Return to Standby
L
H Wiper Up (not recommended)
L
L Wiper Down (not recommended)
Symbol Table
WAVEFORM INPUTS
OUTPUTS
Must be
steady
May change
from Low to
High
May change
from High to
Low
Don’t Care:
Changes
Allowed
N/A
Will be
steady
Will change
from Low to
High
Will change
from High to
Low
Changing:
State Not
Known
Center Line
is High
Impedance
6
FN8187.1
February 4, 2008