REV 1.3.2 1/14/03
Characteristics subject to change without notice.
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Low Noise, Low Power, 32 Taps
X9315
Digitally Controlled Potentiometer (XDCP
™
)
FEATURES
• Solid-state potentiometer
• 3-wire serial interface
• 32 wiper tap points
—Wiper position stored in nonvolatile memory
and recalled on power-up
• 31 resistive elements
—Temperature compensated
—End to end resistance range ± 20%
—Terminal voltage, 0 to V
CC
• Low power CMOS
—V
CC
= 2.7V or 5V
—Active current, 50/400µA max.
—Standby current, 1µA max.
• High reliability
—Endurance, 100,000 data changes per bit
—Register data retention, 100 years
•R
TOTAL
values = 10K
Ω
, 50K
Ω
, 100K
Ω
• Packages
—8-lead SOIC, MSOP and DIP
DESCRIPTION
The Xicor X9315 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 31 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
5-Bit
Up/Down
Counter
5-Bit
Nonvolatile
Memory
Store and
Recall
Control
Circuitry
One
of
Decoder
Resistor
Array
RH/VH
U/D
INC
CS
Transfer
Gates
Thirty
VCC
VSS
RL/VL
RW/VW
Control
and
Memory
Up/Down
(U/D)
Increment
(INC)
Device Select
(CS)
VCC (Supply Voltage)
VSS (Ground)
RH/VH
RW/VW
RL/VL
General
Detailed
0
1
2
28
29
30
31
Two
A
PPLICATION
N
OTE
A V A I L A B L E
AN20 • AN42–53 • AN71 • AN73 • AN88 • AN91–92 • AN99 • AN115 • AN120 • AN124 • AN133 • AN134 • AN135
XDCP
™
is a trademark of Xicor, Inc.
X9315
Characteristics subject to change without notice.
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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
X9315 are equivalent to the fixed terminals of a
mechanical potentiometer. The minimum voltage is
V
SS
and the maximum is V
CC
. 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 200
Ω
at V
CC
= 5V.
Up/Down (U/D)
The U/D input controls the direction of the wiper
movement and whether the counter is incremented 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 X9315
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 X9315: 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
connection 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.
VCC
CS
INC
U/D
RH/VH
VSS
1
2
3
4
8
7
6
5
X9315
DIP/SOIC/MSOP
RL/VL
RW/VW
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
X9315
Characteristics subject to change without notice.
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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 five bit counter. The output of this
counter is decoded to select one of thirty two 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 X9315, 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 power-up/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
X9315
Characteristics subject to change without notice.
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ABSOLUTE MAXIMUM RATINGS
Temperature under bias ....................–65
°
C to +135
°
C
Storage temperature .........................–65°C to +150°C
Voltage on CS, INC, U/D, V
H
, V
L
and
V
CC
with respect to V
SS
.........................–1V to +7V
∆
V = |V
H
–V
L
|........................................................... 5V
Lead temperature (soldering 10 seconds)..........300°C
I
W
(10 seconds) .............................................. ±7.5mA
COMMENT
Stresses above those listed under “Absolute Maximum
Ratings” may cause permanent damage to the device.
This is a stress rating only; the 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 0°C +70°C
Industrial –40°C +85°C
Supply Voltage (V
CC
) Limits
X9315 5V ±10%
X9315-2.7 2.7V to 5.5V
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
/31.
(4) Typical values are for T
A
= 25°C and nominal supply voltage.
(5) This parameter is periodically sampled and not 100% tested
Symbol Parameter
Limits
Test Conditions/NotesMin. Typ. Max. Unit
End to end resistance tolerance ±20 %
V
VH
V
H
terminal voltage 0 V
CC
V
V
VL
V
L
terminal voltage 0 V
CC
V
Power rating 10 mW R
TOTAL
≥
10 K
Ω
R
W
Wiper resistance 200 400
Ω
I
W
= 1mA, VCC = 5V
RWWiper resistance 400 1000 ΩIW = 1mA, VCC = 2.7V
IWWiper current ±3.75 mA
Noise -120 dBV Ref: 1kHz
Resolution 3 %
Absolute linearity(1) ±1 MI(3) Vw(n)(actual)–Vw(n)(expected)
Relative linearity(2) ±0.2 MI(3) Vw(n+1)–[Vw(n)+MI]
RTOTAL temperature coefficient ±300 ppm/°C
Ratiometric temperature coefficient ±20 ppm/°C
CH/CL/CWPotentiometer capacitances 10/10/25 pF See circuit #3
X9315
Characteristics subject to change without notice. 5 of 13
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D.C. OPERATING CHARACTERISTICS (Over recommended operating conditions unless otherwise specified.)
ENDURANCE AND DATA RETENTION
Symbol Parameter
Limits
Unit Test ConditionsMin. Typ.(4) Max.
ICC1 VCC active current (Increment) 50 µA CS = VIL, U/D = VIL or VIH and
INC = 0.4V @ max. tCYC
ICC2 VCC active current (Store) (EE-
PROM Store)
400 µA CS = VIH, U/D = VIL or VIH and
INC = VIH @ max. tWR
ISB Standby supply current 1 µA CS = VCC – 0.3V, U/D and
INC = VSS or VCC – 0.3V
ILI CS, INC, U/D input leakage
current
±10 µA VIN = VSS to VCC
VIH CS, INC, U/D input HIGH voltage VCC x 0.7 VCC + 0.5 V
VIL CS, INC, U/D input LOW voltage –0.5 VCC x 0.1 V
CIN(5) CS, INC, U/D input capacitance 10 pF VCC = 5V, VIN = VSS,
TA = 25°C, 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
VW/RW
VH/RH
VL/RL
VS
Force
Current
VL
VW
Test Point
VH/RH
VW/RW
VL/RL
CH
CL
RW
10pF
10pF
RHRL
RTOTAL
CW
25pF
A.C. CONDITIONS OF TEST
Input pulse levels 0V to 3V
Input rise and fall times 10ns
Input reference levels 1.5V
X9315
Characteristics subject to change without notice. 6 of 13
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A.C. OPERATING CHARACTERISTICS (Over recommended operating conditions unless otherwise specified)
POWER UP AND DOWN REQUIREMENTS
There are no restrictions on the power-up or power-down conditions of VCC and the voltages applied to the
potentiometer pins provided that VCC is always more positive than or equal to VH, VL, and VW, i.e., VCC ≥ VH, VL,
VW. The VCC ramp rate spec is always in effect.
A.C. TIMING
Notes: (6) Typical values are for TA = 25°C and nominal supply voltage.
(7) This parameter is not 100% tested.
(8) MI in the A.C. timing diagram refers to the minimum incremental change in the VW output due to a change in the wiper position.
Symbol Parameter
Limits
UnitMin. Typ.(6) Max.
tCl CS to INC setup 100 ns
tlD INC HIGH to U/D change 100 ns
tDI U/D to INC setup 2.9 µs
tlL INC LOW period 1 µs
tlH INC HIGH period 1 µs
tlC INC Inactive to CS inactive 1 µs
tCPH CS Deselect time (NO STORE) 100 ns
tCPH CS Deselect time (STORE) 10 ms
tIW INC to Vw change 1 5 µs
tCYC INC cycle time 4 µs
tR, tF(7) INC input rise and fall time 500 µs
tPU(7) Power up to wiper stable 5 µs
tR VCC(7) VCC power-up rate 0.2 50 V/ms
tWR Store cycle 5 10 ms
CS
INC
U/D
VW
tCI tIL tIH
tCYC
tID DI
tIW
MI (8)
tIC tCPH
tFtR
10%
90% 90%
(Store)
X9315
Characteristics subject to change without notice. 7 of 13
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PERFORMANCE CHARACTERISTICS (TYPICAL)
Typical Noise
Typical Rtotal vs. Temperature
Typical Total Resistance Temperature Coefficient
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-110
-120
-130
-140
-150
0 102030405060708090100
Frequency (kHz)
Noise (dB)
110 120 130 140 150 160 170 180 190 200
10000
9800
9600
9400
9200
9000
8800
8600
8400
8200
8000
Rtotal
-55 -45 -35 -25 -15 -5 5 15 25 35 45 55 65 75
Temperature 85 95 105 115 125 C°
-55
-350
-300
-250
-200
-150
-100
-50
0
-45 -35 -25 -15 -5 5 15 25 35
Temperature
PPM
45 55 65 75 85 95 105 115 125 °C
X9315
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Typical Wiper Resistance
Typical Absolute% Error per Tap Position
Typical Relative% Error per Tap Position
0
0
100
200
300
400
Rw (Ohms)
500
600
700
800
2 4 6 8 10 12 14 16
Tap
18 20 22 24 26 28 30 32 VCC = 2.7V
40.0%
30.0%
20.0%
10.0%
0.0%
-10.0%
-20.0%
-30.0%
-40.0%
03691215
Tap
Absolute% Error
18 21 24 27 30
20.0%
15.0%
10.0%
5.0%
0.0%
-5.0%
-10.0%
-15.0%
-20.0%
03691215
Relative% Error
18 21 24 27 30
Tap
X9315
Characteristics subject to change without notice. 9 of 13
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APPLICATIONS INFORMATION
Electronic digitally controlled (XDCP) potentiometers provide three powerful application advantages; (1) the
variability 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
VR
VW/RW
VR
I
Three terminal potentiometer;
variable voltage divider Two terminal variable resistor;
variable current
VH
VL
Cascading TechniquesBuffered Reference Voltage
–
+
+5V
R1
+V
–5V
VW
VREF VOUT
OP-07
RW/VW
RW/VW
+V
+V +V
X
(a) (b)
VOUT = VW/RW
Noninverting Amplifier
+
–
VS
VO
R2
R1
VO = (1+R2/R1)VS
LM308A
Voltage Regulator
R1
R2
Iadj
VO (REG) = 1.25V (1+R2/R1)+Iadj R2
VO (REG)VIN 317
Comparator with Hysteresis
VUL = {R1/(R1+R2)} VO(max)
VLL = {R1/(R1+R2)} VO(min)
+
–
VSVO
R2
R1
}
}
LT311A
+5V
–5V
(for additional circuits see AN115)
X9315
Characteristics subject to change without notice. 10 of 13
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PACKAGING INFORMATION
0.118 ± 0.002
(3.00 ± 0.05)
0.040 ± 0.002
(1.02 ± 0.05)
0.150 (3.81)
Ref.
0.193 (4.90)
0.030 (0.76)
0.036 (0.91)
0.032 (0.81)
0.007 (0.18)
0.005 (0.13)
0.008 (0.20)
0.004 (0.10)
0.0216 (0.55)
7° Typ.
R 0.014 (0.36)
0.118 ± 0.002
(3.00 ± 0.05)
0.012 + 0.006 / -0.002
(0.30 + 0.15 / -0.05) 0.0256 (0.65) Typ.
8-Lead Miniature Small Outline Gull Wing Package Type M
NOTE:
1. ALL DIMENSIONS IN INCHES AND (MILLIMETERS)
0.220"
0.0256" Typical
0.025"
Typical
0.020"
Typical
8 PlacesFOOTPRINT
Ref.
X9315
Characteristics subject to change without notice. 11 of 13
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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 Dual In-Line Package Type P
Half Shoulder Width On
All End Pins Optional
.073 (1.84)
Max.
0.325 (8.25)
0.300 (7.62)
Plane
X9315
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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 Gull Wing Package Type S
NOTE: ALL DIMENSIONS IN INCHES (IN PARENTHESES IN MILLIMETERS)
0.250"
0.050"Typical
0.050"
Typical
0.030"
Typical
8 PlacesFOOTPRINT
X9315
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ORDERING INFORMATION
P/N MSOP Part Mark
X9315TM AEJ
X9315TM-2.7 AEI
X9315TMI ADZ
X9315TMI-2.7 ADY
X9315UM AEL
X9315UM-2.7 AEK
X9315UMI AEB
X9315UMI-2.7 AEA
X9315WM AAW
X9315WM-2.7 AAU
X9315WMI AAX
X9315WMI-2.7 AAV
VCC Limits
Blank = 5V ±10%
–2.7 = 2.7V to 5.5V
Temperature Range
Blank = Commercial = 0°C to +70°C
I = Industrial = –40°C to +85°C
Package
M = 8-Lead MSOP
P = 8-Lead Plastic DIP
S = 8-Lead SOIC
End to End Resistance
W = 10KΩ
U = 50KΩ
T = 100K
X9315X X X X
