X9314WM3 XICOR [Xicor Inc.], X9314WM3 Datasheet - Page 3

• Manufacturer Part Number: X9314WM3
• Manufacturer: XICOR [Xicor Inc.]

X9314
DEVICE OPERATION
There are three sections of the X9314: the input control,
counter and decode section; the nonvolatile memory; 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 resistor array to the wiper output. Under the
proper conditions the contents of the counter can be
stored in nonvolatile memory and retained for future use.
The resistor array is comprised of 31 individual resistors
connected in series. At either end of the array and
between each resistor is an electronic switch that
transfers the potential at that point to the wiper.
The INC, U/D and CS inputs control the movement of the
wiper along the resistor array. With CS set LOW the
X9314 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.
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 value of the counter is stored in nonvolatile memory
whenever CS transistions HIGH while the INC input is
also HIGH.
When the X9314 is powered-down, the last counter
position stored will be maintained in the nonvolatile
memory. When power is restored, the contents of the
memory are recalled and the counter is reset to the value
last stored.
SYMBOL TABLE
WAVEFORM
INPUTS
Must be
steady
May change
from LOW
to HIGH
May change
from HIGH
to LOW
Don’t Care:
Changes
Allowed
N/A
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
3
Operation Notes
The system may select the X9314, move the wiper and
deselect the device without having to store the latest
wiper position in nonvolatile memory. The wiper
movement is performed as described above; once the
new position is reached, the system would keep the INC
LOW while taking CS HIGH. The new wiper position
would be maintained until changed by the system or
until a power-up/down cycle recalled the previously
stored data.
This would allow 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,
etc...
The state of U/D may be changed while CS remains
LOW. This allows the host system to enable the X9314
and then move the wiper up and down until the proper
trim is attained.
T
The electronic switches on the X9314 operate in a
“make before break” mode when the wiper changes tap
positions. If the wiper is moved several positions mul-
tiple taps are connected to the wiper for t
change). The R
rarily be reduced by a significant amount if the wiper is
moved several positions.
R
The end to end resistance of the array will fluctuate once
V
IW
CC
TOTAL
/R
is removed.
TOTAL
with V
CC
TOTAL
Removed
value for the device can tempo-
IW
(INC to V
W