X9015US XICOR [Xicor Inc.], X9015US Datasheet - Page 3

• Manufacturer Part Number: X9015US
• Description: Digitally-Controlled Potentiometer
• Manufacturer: XICOR [Xicor Inc.]

X9015
PRINCIPLES OF OPERATION
There are two sections of the X9015: the input control,
counter and decode section; and the resistor array. The
input 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 resis-
tor array to the wiper output. The resistor array is com-
prised of 31 individual resistors connected in series.
The wiper, when at either fixed terminal, acts like its
mechanical equivalent and does not move beyond the
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
change). The R
temporarily be reduced by a significant amount if the
wiper is moved several positions.
When the device is powered-down, the wiper position is
lost. When power is restored, the wiper is set to tap #15.
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 five bit counter. The output of this counter is
decoded to select one of thirty two wiper positions along
the resistive array.
TOTAL
value for the device can
IW
(INC to V
W
3
The system may select the X9015, move the wiper and
deselect the device. The new wiper position will be
maintained until changed by the system or until a power-
up/down cycle.
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
SYMBOL TABLE
CS
H
L
L
WAVEFORM
INC
X
L
U/D
H
X
X
L
INPUTS
Must be
steady
May change
from Low to
High
May change
from High to
Low
Don’t Care:
Changes
Allowed
N/A
Wiper Up
Wiper Down
Standby Current
Return to standby
Mode
OUTPUTS
Will be
steady
Will change
from Low to
High
Will change
from High to
Low
Changing:
State Not
Known
Center Line
is High
Impedance