REV 1.10 4/29/03
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Digitally Controlled Potentiometer (XDCP
TM
) X9318
FEATURES
Solid-state potentiometer
3-wire serial interface
Terminal voltage, 0 to +8V
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
value = 10K
Packages
--8-lead SOIC and DIP
APPLICATIONS
LCD bias control
DC bias adjustment
Gain and offset trim
Laser diode bias control
Voltage regulator output control
DESCRIPTION
The Xicor X9318 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 switch-
ing 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 potentiom-
eter for voltage control or as a two-terminal variable
resistor for current control in a wide variety of applica-
tions.
XDCP is a trademark of Xicor, Inc.
BLOCK DIAGRAM
Up/Down
Counter
7-Bit
Nonvolatile
Memory
Store and
Recall
Control
Circuitry
One
of
One
Decoder
Resistor
Array
R
H
U/D
INC
CS
Wiper
Switches
Hundred
V
CC
V
SS
R
L
R
W
Control
and
Memory
Up/Down
(U/D)
Increment
(INC)
Device Select
(CS)
V
CC
(Supply Voltage)
V
SS
(Ground)
R
H
R
W
R
L
General
Detailed
0
1
2
96
97
98
99
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X9318
PIN CONFIGURATION
ORDERING INFO
PIN DESCRIPTIONS
Ordering
Number
RTOTAL
Package
Operating Temperature
Range
X9318WS8
10Kohm
8-lead SOIC
0C to 70C
X9318WS8I
10Kohm
8-lead SOIC
-40C to +85C
X9318WP8
10Kohm
8-lead Plastic DIP
0C to 70C
X9318WP8I
10Kohm
8-lead Plastic DIP
-40C to +85C
DIP/
SOIC
Symbol
Brief Description
1
INC
Increment
. Toggling INC while CS is low moves the wiper either up or down.
2
U/D
Up/Down
. The U/D input controls the direction of the wiper movement.
3
R
H
The high terminal is equivalent to one of the fixed terminals of a mechanical potentiometer.
4
V
SS
Ground.
5
R
W
The wiper terminal is equivalent to the movable terminal of a mechanical potentiometer.
6
R
L
The low terminal is equivalent to one of the fixed terminals of a mechanical potentiometer.
7
CS
Chip Select
. The device is selected when the CS input is LOW, and de-selected when CS is
high.
8
V
CC
Supply Voltage.
R
H
V
CC
INC
U/D
1
2
3
4
8
7
6
5
X9318
DIP/SOIC
V
SS
CS
R
L
R
W
Operating Temperature Range
Blank = Commercial = 0
C to +70C
I = Industrial = 40
C to +85C
Package
P = 8-Lead Plastic DIP
S = 8-Lead SOIC
End to End Resistance
W =
10K
X9318X
X
X
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X9318
ABSOLUTE MAXIMUM RATINGS
Junction 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
R
H
, R
W
, R
L
to ground .......................................... +10V
Lead temperature (soldering 10 seconds)..........300C
I
W
(10 seconds) ................................................. 6mA
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 con-
ditions for extended periods may affect device reliability.
POTENTIOMETER CHARACTERISTICS
(V
CC
= 5V 10%, T
A
= Full Operating Temperature Range unless otherwise stated)
Symbol
Parameter
Limits
Test Conditions/Notes
Min.
Typ.
(4)
Max.
Unit
End to end resistance tolerance
-20
+20
%
See ordering information
for values
V
RH
/
RL
R
H
/R
L
terminal voltage
V
SS
8
V
V
SS
= 0V
Power rating
25
mW
R
W
Wiper resistance
40
200
I
W
= 1mA
I
W
Wiper current
(5)
-3.0
+3.0
mA
See test circuit
Noise
(7)
-120
dBV
Ref: 1kHz
Resolution
1
%
Absolute linearity
(1)
-1
+1
MI
(3)
V(RH) = 8V,
V(RL) = 0V
Relative linearity
(2)
-0.2
+0.2
MI
(3)
R
TOTAL
temperature coefficient
(5)
300
ppm/C
Ratiometric temperature coefficient
(5),(6)
-20
+20
ppm/C
C
H
/C
L
/C
W
(5)
Potentiometer capacitances
10/10/25
pF
See equivalent circuit
V
CC
Supply Voltage
4.5
5.5
V
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X9318
D.C. OPERATING CHARACTERISTICS
(V
CC
= 5V 10%, T
A
= Full Operating Temperature Range unless otherwise stated)
ENDURANCE AND DATA RETENTION
(V
CC
= 5V 10%, T
A
= Full Operating Temperature Range)
Notes:
(1) Absolute linearity is utilized to determine actual wiper voltage versus expected voltage = [V(R
W(n)(actual)
)V(R
W(n)(expected)
)]/MI
V(R
W(n)(expected)
) = n(V(R
H
)-V(R
L
))/99 + V(R
L
), with n from 0 to 99.
(2) Relative linearity is a measure of the error in step size between taps = [V(R
W(n+1)
)(V(R
W(n)
) MI)]/MI
(3) 1 Ml = Minimum Increment = [V(R
H
)V(R
L
)]/99.
(4) Typical values are for T
A
= 25C and nominal supply voltage.
(5) This parameter is not 100% tested.
(6) Ratiometric temperature coefficient = (V(R
W
)
T1(n)
V(R
W
)
T2(n)
)/[V(R
W
)
T1(n)
(T1T2) x 10
6
], with T1 & T2 being 2 temperatures, and
n from 0 to 99.
(7) Measured with wiper at tap position 31, R
L
grounded, using test circuit.
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 @ min. t
CYC
R
L
, R
H
, R
W
not connected
I
SB
Standby supply current
300
1000
A
CS
2.4V, U/D and INC = 0.4V
R
L
, R
H
, R
W
not connected
I
LI
CS, INC, U/D input leakage cur-
rent
-10
+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
Equivalent Circuit
Force
Current
Test Point
R
W
C
H
C
L
R
W
10pF
10pF
R
TOTAL
C
W
25pF
R
H
R
L
A.C. CONDITIONS OF TEST
Input pulse levels
0.8V to 2.0V
Input rise and fall times
10ns
Input reference levels
1.4V
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X9318
A.C. OPERATING CHARACTERISTICS
(V
CC
= 5V 10%, T
A
= Full Operating Temperature Range unless otherwise stated)
POWER UP AND DOWN REQUIREMENTS
The recommended power up sequence is to apply V
CC
/V
SS
first, then the potentiometer voltages. During power-
up, the data sheet parameters for the DCP do not fully apply until 1 millisecond after V
CC
reaches its final value.
The V
CC
ramp spec is always in effect. In order to prevent unwanted tap position changes, or an inadvertant store,
bring the CS and INC high before or concurrently with the V
CC
pin on powerup.
A.C. TIMING
Symbol
Parameter
Limits
Unit
Min.
Typ.
(4)
Max.
t
Cl
CS to INC setup
100
ns
t
lD
(5)
INC HIGH to U/D change
100
ns
t
DI
(5)
U/D to INC setup
1
s
t
lL
INC LOW period
1
s
t
lH
INC HIGH period
1
s
t
lC
INC inactive to CS inactive
1
s
t
CPHS
CS deselect time (STORE)
20
ms
t
CPHNS
(5)
CS deselect time (NO STORE)
1
s
t
IW
INC to R
W
change
100
500
s
t
CYC
INC cycle time
4
s
t
R,
t
F
(5)
INC input rise and fall time
500
s
t
PU
(5)
Power up to wiper stable
500
s
t
R
V
CC
(5)
V
CC
power-up rate
0.2
50
V/ms
CS
INC
U/D
R
W
t
CI
t
IL
t
IH
t
CYC
t
ID
t
DI
t
IW
MI
(3)
t
IC
t
CPHS
t
F
t
R
10%
90%
90%
t
CPHNS
X9318
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PIN DESCRIPTIONS
R
H
and R
L
The high (R
H
) and low (R
L
) terminals of the X9318 are
equivalent to the fixed terminals of a mechanical
potentiometer. The terminology of R
L
and R
H
refer-
ences 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
R
w
is the wiper terminal and is equivalent to the mov-
able terminal of a mechanical potentiometer. The posi-
tion 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 move-
ment and whether the counter is incremented or decre-
mented.
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 X9318
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 X9318: the control
section, the nonvolatile memory, and the resistor array.
The 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. 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.
Electronic switches at either end of the array and
between each resistor provide an electrical connection
to the wiper pin, R
W
.
The wiper acts like its mechanical equivalent and does
not move beyond the first or 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 tem-
porarily be reduced by a significant amount if the wiper
is moved several positions.
When the device is powered-down, the last wiper posi-
tion stored will be maintained in the nonvolatile mem-
ory. When power is restored, the contents of the
memory are recalled and the wiper is set to the value
last stored.
R
H
V
CC
INC
U/D
1
2
3
4
8
7
6
5
X9318
DIP/SOIC
V
SS
CS
R
L
R
W
Symbol
Description
R
H
High terminal
R
W
Wiper terminal
R
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
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X9318
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 X9318, 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 prefer-
ence, 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
CS
INC
U/D
Mode
L
H
Wiper up
L
L
Wiper down
H
X
Store wiper position to
nonvolatile memory
H
X
X
Standby
L
X
No store, return to standby
L
H
Wiper Up (not recommended)
L
L
Wiper Down
(not recommended)
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X9318
APPLICATIONS INFORMATION
Electronic digitally controlled (XDCP) potentiometers provide three powerful application advantages; (1) the vari-
ability and reliability of a solid-state potentiometer, (2) the flexibility of computer-based digital controls, and (3) the
retentivity of nonvolatile memory used for the storage of multiple potentiometer settings or data.
Basic Configurations of Electronic Potentiometers
Basic Circuits
V
REF
R
W
V
REF
I
Three terminal potentiometer;
variable voltage divider
Two terminal variable resistor;
variable current
R
H
R
L
Cascading Techniques
Buffered Reference Voltage
+
+5V
R
1
+V
V
REF
V
OUT
LMC7101
R
W
R
W
+V
+V
+V
X
(a)
(b)
V
OUT
= V
W
/R
W
Single Supply Inverting Amplifier
Voltage Regulator
R
1
R
2
I
adj
V
O
(REG) = 1.25V (1+R
2
/R
1
)+I
adj
R
2
V
O
(REG)
V
IN
317
Offset Voltage Adjustment
+
V
S
V
O
R
2
R
1
100K
10K
10K
10K
+12V
LMC7101
Comparator with Hysteresis
V
UL
= {R
1
/(R
1
+R
2
)} V
O
(max)
V
LL
= {R
1
/(R
1
+R
2
)} V
O
(min)
+
R
1
V
O
LMC7101
+
V
S
V
O
R
2
R
1
}
}
LT311A
(for additional circuits see AN115)
+12V
R
2
+8V
100K
100K
+8V
V
S
V
O
= (R2/R1)V
S
R
W
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X9318
PACKAGING INFORMATION
0.150 (3.80)
0.158 (4.00)
0.228 (5.80)
0.244 (6.20)
0.014 (0.35)
0.019 (0.49)
Pin 1
Pin 1 Index
0.010 (0.25)
0.020 (0.50)
0.050 (1.27)
0.188 (4.78)
0.197 (5.00)
0.004 (0.19)
0.010 (0.25)
0.053 (1.35)
0.069 (1.75)
(4X) 7
0.016 (0.410)
0.037 (0.937)
0.0075 (0.19)
0.010 (0.25)
0 - 8
X 45
8-Lead Plastic Small Outline Package, Type S (8-lead SOIC)
NOTE: ALL DIMENSIONS IN INCHES (IN PARENTHESES IN MILLIMETERS)
0.250"
0.050"Typical
0.050"
Typical
0.030"
Typical
8 Places
FOOTPRINT
Characteristics subject to change without notice.
10 of 10
LIMITED WARRANTY
Devices sold by Xicor, Inc. are covered by the warranty and patent indemnification provisions appearing in its Terms of Sale only. Xicor, Inc. makes no warranty,
express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement.
Xicor, Inc. makes no warranty of merchantability or fitness for any purpose. Xicor, Inc. reserves the right to discontinue production and change specifications and prices
at any time and without notice.
Xicor, Inc. assumes no responsibility for the use of any circuitry other than circuitry embodied in a Xicor, Inc. product. No other circuits, patents, or licenses are implied.
TRADEMARK DISCLAIMER:
Xicor and the Xicor logo are registered trademarks of Xicor, Inc. AutoStore, Direct Write, Block Lock, SerialFlash, MPS, BiasLock and XDCP are also trademarks of
Xicor, Inc. All others belong to their respective owners.
U.S. PATENTS
Xicor products are covered by one or more of the following U.S. Patents: 4,326,134; 4,393,481; 4,404,475; 4,450,402; 4,486,769; 4,488,060; 4,520,461; 4,533,846;
4,599,706; 4,617,652; 4,668,932; 4,752,912; 4,829,482; 4,874,967; 4,883,976; 4,980,859; 5,012,132; 5,003,197; 5,023,694; 5,084,667; 5,153,880; 5,153,691;
5,161,137; 5,219,774; 5,270,927; 5,324,676; 5,434,396; 5,544,103; 5,587,573; 5,835,409; 5,977,585. Foreign patents and additional patents pending.
LIFE RELATED POLICY
In situations where semiconductor component failure may endanger life, system designers using this product should design the system with appropriate error detection
and correction, redundancy and back-up features to prevent such an occurrence.
Xicor's products are not authorized for use in critical components in life support devices or systems.
1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to
perform, when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user.
2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life
support device or system, or to affect its safety or effectiveness.
Xicor, Inc. 2003 Patents Pending
REV 1.10 4/29/03
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X9318
PACKAGING INFORMATION
NOTE:
1. ALL DIMENSIONS IN INCHES (IN PARENTHESES IN MILLIMETERS)
2. PACKAGE DIMENSIONS EXCLUDE MOLDING FLASH
0.020 (0.51)
0.016 (0.41)
0.150 (3.81)
0.125 (3.18)
0.110 (2.79)
0.090 (2.29)
0.430 (10.92)
0.360 (9.14)
0.300
(7.62) Ref.
Pin 1 Index
0.145 (3.68)
0.128 (3.25)
0.025 (0.64)
0.015 (0.38)
Pin 1
Seating
0.065 (1.65)
0.045 (1.14)
0.260 (6.60)
0.240 (6.10)
0.060 (1.52)
0.020 (0.51)
Typ. 0.010 (0.25)
0
15
8-Lead Plastic, DIP, Package Code P8
Half Shoulder Width On
All End Pins Optional
.073 (1.84)
Max.
0.325 (8.25)
0.300 (7.62)
Plane
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