X9312 Datasheet, PDF (2/9 Pages) Xicor Inc. – E2POT™ Nonvolatile Digital Potentiometer

X9312
PIN DESCRIPTIONS
R_H/V_H and R_L/V_L
The high (R_H/V_H) and low (R_L/V_L) terminals of the
X9312 are equivalent to the fixed terminals of a
mechanical potentiometer. The minimum voltage is 0V
and the maximum is +15V. The terminology of R_L/V_L
and R_H/V_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 /V
WW
R_w/V_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 incriminated 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 X9312
will be placed in the low power standby mode until the
device is selected once again.
PIN CONFIGURATION
INC
U/D
R_H/V_H
V_SS
DIP/SOIC
1
8
2 _X9312 7
3
6
4
5
V_CC
CS
R_L/V_L
R_W/V_W
PIN NAMES
Symbol
R_H/V_H
R_W/V_W
R_L/V_L
V_SS
V_CC
U/D
INC
CS
Description
High terminal
Wiper terminal
Low terminal
Ground
Supply voltage
Up/Down control input
Increment control input
Chip select control input
PRINCIPLES OF OPERATION
There are three sections of the X9312: 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 99 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 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_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.
2
FN8176.0
March 15, 2005