Not Recommended for New Designs
REV 1.1.3 8/20/02
Characteristics subject to change without notice.
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Terminal Voltage 0V to +15V, 100 Taps
X9312
Digitally Controlled Potentiometer (XDCP
TM
)
FEATURES
Solid-state potentiometer
3-wire serial interface
Terminal voltage, 0 to +15V
100 wiper tap points
--Wiper position stored in nonvolatile memory
and recalled on power-up
99 resistive elements
--Temperature compensated
--End to end resistance range 20%
Low power CMOS
--V
CC
= 5V
--Active current, 3mA max.
--Standby current, 1mA max.
High reliability
--Endurance, 100,000 data changes per bit
--Register data retention, 100 years
R
TOTAL
values = 10K
,
50K
,
and 100K
Packages
--8-lead SOIC and DIP
DESCRIPTION
The Xicor X9312 is a digitally controlled potentiometer
(XDCP). The device consists of a resistor array, wiper
switches, a control section, and nonvolatile memory.
The wiper position is controlled by a 3-wire interface.
The potentiometer is implemented by a resistor array
composed of 99 resistive elements and a wiper
switching network. Between each element and at
either end are tap points accessible to the wiper
terminal. The position of the wiper element is
controlled by the CS, U/D, and INC inputs. The
position of the wiper can be stored in nonvolatile
memory and then be recalled upon a subsequent
power-up operation.
The device can be used as a three-terminal
potentiometer or as a two-terminal variable resistor in
a wide variety of applications including:
control
parameter adjustments
signal processing
BLOCK DIAGRAM
7-Bit
Up/Down
Counter
7-Bit
Nonvolatile
Memory
Store and
Recall
Control
Circuitry
One
of
One
Decoder
Resistor
Array
R
H
/V
H
U/D
INC
CS
Transfer
Gates
Hundred
V
CC
V
SS
R
L
/V
L
R
W
/V
W
Control
and
Memory
Up/Down
(U/D)
Increment
(INC)
Device Select
(CS)
V
CC
(Supply Voltage)
V
SS
(Ground)
R
H
/V
H
R
W
/V
W
R
L
/V
L
General
Detailed
0
1
2
96
97
98
99
XDCP is a trademark of Xicor, Inc.
A
PPLICATION
N
OTE
A V A I L A B L E
AN20 AN4253 AN71 AN73 AN88 AN9192 AN99 AN115 AN120 AN124 AN133 AN134 AN135
Not Recommended for New Designs
X9312
Characteristics subject to change without notice.
2 of 9
REV 1.1.3 8/20/02
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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
W
/V
W
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 40
.
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
PIN NAMES
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.
R
H
/V
H
V
CC
INC
U/D
1
2
3
4
8
7
6
5
X9312
DIP/SOIC
V
SS
CS
R
L
/V
L
R
W
/V
W
Symbol
Description
R
H
/V
H
High terminal
R
W
/V
W
Wiper terminal
R
L
/V
L
Low terminal
V
SS
Ground
V
CC
Supply voltage
U/D
Up/Down control input
INC
Increment control input
CS
Chip select control input
Not Recommended for New Designs
X9312
Characteristics subject to change without notice.
3 of 9
REV 1.1.3 8/20/02
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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
memory whenever CS transitions HIGH while the INC
input is also HIGH.
The system may select the X9312, move the wiper
and deselect the device without having to store the
latest 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
system or until a powerup/down cycle recalled the
previously 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
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 device
and then move the wiper up and down until the proper
trim is attained.
MODE SELECTION
SYMBOL TABLE
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
WAVEFORM
INPUTS
OUTPUTS
Must be
steady
Will be
steady
May change
from Low to
High
Will change
from Low to
High
May change
from High to
Low
Will change
from High to
Low
Don't Care:
Changes
Allowed
Changing:
State Not
Known
N/A
Center Line
is High
Impedance
Not Recommended for New Designs
X9312
Characteristics subject to change without notice.
4 of 9
REV 1.1.3 8/20/02
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ABSOLUTE MAXIMUM RATINGS
Temperature under bias ....................65
C to +135
C
Storage temperature .........................65C to +150C
Voltage on CS, INC, U/D and V
CC
with respect to V
SS
................................. 1V to +7V
V = |V
H
V
L
|......................................................... 15V
Lead temperature (soldering 10 seconds)..........300C
I
W
(10 seconds) .............................................. 8.8mA
COMMENT
Stresses above those listed under "Absolute Maximum
Ratings" may cause permanent damage to the device.
This is a stress rating only; functional operation of the
device (at these or any other conditions above those
listed in the operational sections of this specification) is
not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device
reliability.
RECOMMENDED OPERATING CONDITIONS
Temperature
Min.
Max.
Commercial
0C
+70C
Industrial
40C
+85C
Supply Voltage (V
CC
)
Limits
X9312
5V 10%
POTENTIOMETER CHARACTERISTICS
(Over recommended operating conditions unless otherwise stated.)
Notes:
(1) Absolute linearity is utilized to determine actual wiper voltage versus expected voltage = (V
w(n)
(actual)V
w(n)
(expected)) = 1 Ml
Maximum.
(2) Relative linearity is a measure of the error in step size between taps = R
W(n+1)
[R
w(n)
+ Ml] = 0.2 Ml.
(3) 1 Ml = Minimum Increment = R
TOT
/99.
Symbol
Parameter
Limits
Test Conditions/Notes
Min.
Typ.
Max.
Unit
End to end resistance tolerance
20
%
V
VH
V
H
terminal voltage
V
SS
15
V
V
SS
= 0V
V
VL
V
L
terminal voltage
V
SS
15
V
V
SS
= 0V
Power rating
25
mW
R
TOTAL
10 K
Power rating
225
mW
R
TOTAL
= 1 K
R
W
Wiper resistance
40
100
I
W
= 1mA, V
CC
= 5V
I
W
Wiper current
4.4
mA
Noise
-120
dBV
Ref: 1kHz
Resolution
1
%
Absolute linearity
(1)
1
MI
(3)
R
w(n)(actual)
R
w(n)(expected)
Relative linearity
(2)
0.2
MI
(3)
R
w(n+1)
[R
w(n)+MI
]
R
TOTAL
temperature coefficient
300
ppm/C
Ratiometric temperature coefficient
20
ppm/C
C
H
/C
L
/C
W
Potentiometer capacitances
10/10/25
pF
See circuit #3
Not Recommended for New Designs
X9312
Characteristics subject to change without notice.
5 of 9
REV 1.1.3 8/20/02
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D.C. OPERATING CHARACTERISTICS (Over recommended operating conditions unless otherwise specified.)
ENDURANCE AND DATA RETENTION
Notes: (4) Typical values are for T
A
= 25C and nominal supply voltage.
(5) This parameter is periodically sampled and not 100% tested.
Symbol
Parameter
Limits
Unit
Test Conditions
Min.
Typ.
(4)
Max.
I
CC
V
CC
active current (Increment)
1
3
mA
CS = V
IL
, U/D = V
IL
or V
IH
and
INC = 0.4V/2.4V @ max. t
CYC
I
SB
Standby supply current
500
1000
A
CS = V
CC
0.3V, U/D and
INC = V
SS
or V
CC
0.3V
I
LI
CS, INC, U/D input leakage current
10
A
V
IN
= V
SS
to V
CC
V
IH
CS, INC, U/D input HIGH voltage
2
V
CC
+ 1
V
V
IL
CS, INC, U/D input LOW voltage
1
0.8
V
C
IN
(5)
CS, INC, U/D input capacitance
10
pF
V
CC
= 5V, V
IN
= V
SS
, T
A
= 25C,
f = 1MHz
Parameter
Min.
Unit
Minimum endurance
100,000
Data changes per bit
Data retention
100
Years
Test Circuit #1
Test Circuit #2
Circuit #3 SPICE Macro Model
Test Point
V
W
/R
W
V
H
/R
H
V
L
/R
L
V
S
Force
Current
L
VW
Test Point
V
H
/R
H
V
W
/R
W
V
L
/R
L
C
H
C
L
R
W
10pF
10pF
R
H
R
L
R
TOTAL
C
W
25pF
A.C. CONDITIONS OF TEST
Input pulse levels
0V to 3V
Input rise and fall times
10ns
Input reference levels
1.5V
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