X9C102_06 Datasheet, PDF (8/11 Pages) Intersil Corporation – Digitally Controlled Potentiometer

X9C102, X9C103, X9C104, X9C503
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) a 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 mem-
ory whenever CS transitions HIGH while the INC input
is also HIGH.
The system may select the X9Cxxx, move the wiper,
and deselect the device without having to store the lat-
est wiper position in nonvolatile memory. After the
wiper movement is performed as described above 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 sys-
tem or until a power-down/up cycle recalled the previ-
ously stored data.
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 pref-
erence: system parameter changes due to tempera-
ture drift, etc...
The state of U/D may be changed while CS remains
LOW. This allows the host system to enable the
device and then move the 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
8
FN8222.1
December 20, 2006